Let's break this down a bit...
First, as has been pointed out by many on this thread, it's in the OT part of the Bible, it is not a "current" requirement in the NT. It is no longer required as under the OT.
Second, LdS "do it" if they want to be found worthy of a temple recommend. If you don't get a temple recommend, you can't take out your endowments. If you can't take out your endowments, you don't get the promise of the celestial kingdom.
If you don't get to the celestial kingdom, there's no dwelling with god or your eternal family, there's no dwelling with your eternal god, there's no birthing of spirit babies to populate your eternal huusband's (god) planet.
Now tell us again, do you "do it" because you "want to" or because you need to if you want to receive "all the blessings" (celestial kingdom)?
And has been pointed out, not "all Christians" "obey" the OT requirement by making it a requirement for exaltation as the LdS do.
I like to pay my tithe. I tithed when I was a Baptist and I tithed when I was a Pentecostal. It’s what I do. It’s the only area where God says it’s OK to test Him - if He will not pour you out a Blessing . . .
But that’s not why I tithe.
You do not have to tithe; that’s your choise. No problem. What’s the beef?
Why do you care if I tithe or not?