While much of the Old Testament law itself doesn't apply to Christians, it nevertheless has value to us today, since the Old Testament is described to us as God Breathed, amongst other true things.
To see what applies to us today, read the following article: http://answering-judaism.blogspot.co.uk/2013/11/observance-of-torah-demanded-of-gentiles.html
The Old Testament in its context shows God as one who wants worship to be conducted in an orderly manner HE decreed it. I put the emphasis on he because on many occasions, churches will often say "Well scripture doesn't condemn it but whose to say its wrong?".
Here are some examples:
"Deuteronomy 5:1 Moses summoned all Israel and said:
Hear, Israel, the decrees and laws I declare in your hearing today. Learn them and be sure to follow them. 2 The Lord our God made a covenant with us at Horeb. 3 It was not with our ancestors[a] that the Lord made this covenant, but with us, with all of us who are alive here today. 4 The Lord spoke to you face to face out of the fire on the mountain."
"Deuteronomy 10:12 And now, Israel, what does the Lord your God ask of you but to fear the Lord your God, to walk in obedience to him, to love him, to serve the Lord your God with all your heart and with all your soul, 13 and to observe the Lord’s commands and decrees that I am giving you today for your own good?"
"Deuteronomy 6:17 Be sure to keep the commands of the Lord your God and the stipulations and decrees he has given you. 18 Do what is right and good in the Lord’s sight, so that it may go well with you and you may go in and take over the good land the Lord promised on oath to your ancestors, 19 thrusting out all your enemies before you, as the Lord said."
"Exodus 40:12 “Bring Aaron and his sons to the entrance to the tent of meeting and wash them with water. 13 Then dress Aaron in the sacred garments, anoint him and consecrate him so he may serve me as priest. 14 Bring his sons and dress them in tunics. 15 Anoint them just as you anointed their father, so they may serve me as priests. Their anointing will be to a priesthood that will continue throughout their generations.” 16 Moses did everything just as the Lord commanded him."
But that's my point, Shouldn't man be asking God of guidance through his word, or even consulting him directly what his will is?
Yes, there are things not directly addressed in scripture, but you must ask yourself if they are truly God honouring, otherwise you'll end up reducing church leadership to something that is a play thing or let's say removing from the parents responsibility to raise their children up in the way of the Lord.
It must be determined if something is an acceptable practice and not simply because it seems good or fits our thinking, but whether or not the practice is something that is right in the Lord's sight.
David Pawson once posed an interesting question that has relevance here namely "What does God feel about it?" That question should resonate with every Christian hears or reads the question itself.
Think on this.