The whole idea is rather odd, but it's not like there's never been music in Trek that goes outside of theme songs and incidental music. I think what I dislike the most about it is the concept of it being a regular thing. Why not have it, but as a rare occurrence? Bring in whoever - dress them up as crew members and make it some sort of - the crew is getting a well-deserved break - or whatever. Hell, I actually write a pair of E2 crew members as playing guitar and singing because you've got a century to kill so why not do a little coffee house kind of act? But it would have to be small.
Part II of an E2 two-parter (try saying that three times fast) - Archer: How'd you entertain yourselves over the course of a century? I mean, other than having kids and dodging the Xindi? Karyn: We turned the Observation Lounge into a performance space. Some of the intervening generations, well, you know not everyone is into science. Some of them turned out to be really artistic, and musically talented. My Uncle Pete is; c'mon and I'll take you.