[1] Because exceptions on the 68000 didn't save enough information to restart the faulting instruction. You could get around this, but it involved using two 68000s as insane hack ...
The EC variant was available right through to the 060, and I'd be curious to know how prevalent the line was. I suspect the EC versions far outnumbered the "full" chips, because they appeared in all kinds of industrial systems. I'm basing that entirely on working for a company that was still shipping products with MMU-less 68k and coldfire this century, not any real data.
There were huge numbers of embedded 68k family chips shipped, although I've never seen the actual numbers. Folks went from 68000 to 68ec020 to 68ec060 as a (sorta) easy upgrade path. They're still made if you count the 68sec000, and the 68300 line is the spiritual successor.
Whether the Motorola MMU for the 68010 (the 68451) was sane or not is a matter of some debate. The 68451 was definitely slow and limited (segments, not pages); in the end, most vendors rolled their own MMU out of static RAM and PALs.