But it is never actually made clear what the purpose of this "new name" is, apart from as a "key word" at the veil. Assuming the whole ceremony is symbolic and not literally exactly how it will be (though not all Mormons reject a literal interpretation!) then where does this "new name" fit in with the eternal progression plan?
Also, given that it is no secret even amongst Mormons that each "new name" is given to everybody who goes through the temple on that day, then the new name can't possibly have been your "pre-existence" name (unless, by chance, everybody with the same pre-existing name went through the temple on Earth on the exact same day!) so do Mormons really believe that the new name, that you will always be known as, is determined by nothing more than chance?
Nope, it doesn't make sense - and it didn't make sense at the time when I was a believer. I just put in on the shelf then marked "things that don't make sense now but will when God reveals it"