All that matters to Luther for the Mass was the Words of Institution and faith

But in all these matters we will want to beware lest we make binding what should be free, or make sinners of those who may do some things differently or omit others. All that matters is that the Words of Institution should be kept intact and that everything should be done by faith. For these rites are supposed to be for Christians…who observe them voluntarily and from the heart, but are free to change them how and when ever they may wish. Therefore, it is not in these matters that anyone should either seek or establish as law some indispensable form by which he might ensnare or harass consciences. Nor do we find any evidence for such an established rite, either in the early fathers or in the primitive church, but only in the Roman church. But even if they had decreed anything in this matter as a law, we would not have to observe it, because these things neither can nor should be bound by laws.

Martin Luther
An Order of Mass and Communion for the Church at Wittenberg

Luther states that Christ does not really care about worship style

I have no intention of cramping anyone’s freedom or of introducing a law that might again lead to superstition. Christ will not care very much about these matters, nor are they worth arguing about.

Martin Luther
An Order of Mass and Communion for the Church at Wittenberg

Luther didn’t change worship style more only because the people couldn’t handle it

Until now I have only used books and sermons to wean the hearts of people from their godless regard for ceremonial… For I have been hesitant and fearful, partly because of the weak in faith, who cannot suddenly exchange an old and accustomed order of worship for a new and unusual one, and more so because of the fickle and fastidious spirits who rush in like unclean swine without faith or reason, and who delight only in novelty and tire of it as quickly, when it has worn off. Such people are a nuisance even in other affairs, but in spiritual matters, they are absolutely unbearable. Nonetheless, at the risk of bursting with anger, I must bear with them, unless I want to let the gospel itself be denied to the people.

Martin Luther
An Order of Mass and Communion for the Church at Wittenberg

Luther advises worship styles and traditions as mutable and optional

This is my advice: If your lord, the margrave and elector, etc., permits the gospel of Jesus Christ to be preached with purity and power and without human additions and the two sacraments of Baptism and the Body and Blood of Jesus Christ to be administered and offered according to their institution…go along in God’s name and carry a silver or gold cross and wear a cope or alb of velvet, silk, or linen. And if one cope or alb is not enough for your lord, the elector, wear three of them…Moreover, if His Grace is not satisfied that you go about singing and ringing bells in procession only once, go about seven times…If your lord, the margrave, desires it, let His Grace leap and dance at the head of the procession with harps, drums, cymbals, and bells…I am fully satisfied, for none of these things (as long as no abuse is connected with them) adds anything to the gospel or detracts from it. Only do not let such things be regarded as necessary for salvation and thus bind the consciences of men…Only what God commands is necessary; the rest is free.

Martin Luther
Letters of Spiritual Counsel

Luther on stripping ceremonials from the Mass

In the first place, in order that we might safely and happily attain to a true and free knowledge of this sacrament, we must be particularly careful to put aside whatever has been added to its original simple institution by the zeal and devotion of men: such as vestments, ornaments, chants, prayers, organs, candles, and the whole pageantry of outward things… All the rest is the work of man, added to the word of Christ and the mass can be held and remain a mass just as well without them.

Martin Luther
The Babylonian Captivity of the Church

Without the words of the Gospel, everything else in the mass is useless

And now it has finally come to this: the chief thing in the mass has been forgotten, and nothing is remembered except the additions of men! … Indeed, the greatest and most useful art is to know what really and essentially belongs to the mass, and what is added and foreign to it. For where there is no clear distinction, the eyes and the heart are easily misled by such sham into a false impression and delusion. Then what men have contrived is considered the mass; and what the mass really is, is never experienced, to say nothing of deriving benefit from it … If we desire to observe mass properly and to understand it, then we must surrender everything that the eyes behold and that the senses suggest – be it vestments, bells, songs, ornaments, prayers, processions, elevations, prostrations, or whatever happens in the mass – until we first grasp and thoroughly ponder the words of Christ, by which he performed and instituted the mass and commanded us to perform it. For therein lies the whole mass, its nature, work, profit, and benefit. Without the words nothing is derived from the mass.

Martin Luther
A Treatise On The New Testament, That Is, The Holy Mass.

Luther exhorts his flock to private confession

So if there is a heart that feels its sin and desires comfort, it has here a sure refuge where it finds and hears God’s Word because through a human being God looses and absolves from sin….We urge you, however, to confess and express your needs, not for the purpose of performing a work but to hear what God wants to say to you. The Word or absolution, I say, is what you should concentrate on, magnifying and cherishing it as a great and wonderful treasure to be accepted with all praise and gratitude. …

Thus we teach what a wonderful, precious, comforting thing confession is, and we urge that such a precious blessing should not be despised, especially when we consider our great need. If you are a Christian, you need neither my compulsion nor the pope’s command at any point, but you will force yourself to go and ask me that you may share in it. However, if you despise it and proudly stay away from confession, then we must come to the conclusion that you are not a Christian and that you also ought not receive the sacrament [of the Altar]. For you despise what no Christian ought to despise, and you show thereby that you can have no forgiveness of sin. …

If you are a Christian, you should be glad to run more than a hundred miles for confession, not under compulsion but rather coming and compelling us to offer it. For here the compulsion must be reversed; we are the ones who must come under the command and you must come in freedom. We compel no one, but allow ourselves to be compelled, just as we are compelled to preach and administer the sacrament.

Therefore, when I exhort you to go to confession, I am doing nothing but exhorting you to be a Christian….For those who really want to be upright Christians and free from their sins, and who want to have a joyful conscience, truly hunger and thirst already.

Martin Luther
Book of Concord: A Brief Admonition to Confession