One of the issues about mesh in SL is the extent to which they count against a region's prim count. Unfortunately, it sounds like the mapping makes meshes so expensive that people may decide they're not worth it. See "The Death of SL Mesh" on the Heart Botanicals blog, and this thread in the SL mesh forum for more discussion.
UPDATE: Miriel Enfleld, maker of amazing things in SL who gave up on it when she felt she'd done all she could with the tools SL provided, has posted in the SL mesh forum thread. Mesh has tempted her to re-enter SL, but the insane PE (prim equivalent, I think) mapping may kill off that temptation, much to SL's loss. WTF is LL thinking?