I actually really like it. I think it's kind of funny too, and it's something Weezer would definitely do. And maybe they didn't put some of those songs on because they are still in contention for other Weezer albums.
If you remember during the recording of Make Believe Rivers said he was really into over-dramatic power ballads and that influenced his writing at that time (I think you can really see this in Make Believe - the songs seem 'emotional' in a very impersonal way, like most Unbreak My Heart-esque ballads). I think it's included as the bands take on it kind of sums up where they were at that time. Also, this has been a highly demanded track since it was first announced (I think at some point people thought it would be an album track or at least b-side on Make Believe). Finally, it's exactly the type of song that will bet publicity for the band (like Kids/Pokerface) and possibly raise interest in the album.
To be honest, if you pretend it isn't a Toni Braxton song I bet many people would consider it a very strong song from that era.