The percent indicator is mildly helpful, but sometimes those last couple of percent seem to take forever when you have 200,000+ in the selection. Seeing exactly how many frames in total would help ease my mind. At least that's my theory. :-)
I've thought this too, and it would be nice. But honestly, looking at the length of the video and multiplying by 29.97002997 (for NTSC anyway) only takes a couple seconds. You do keep a calculator handy, right?