There are a good 30+ mini scale mech files out there and I found about 10 vehicles as well.
Can you post a list? First, I have zero issue with MWO Mechs appearing on the table...
as long as people can tell what they are. There are some real issues with some of the MWO designs looking similar at a distance (particularly the medium-class humanoids) because several have similar broadly similar outlines and their panel density and configurations are very similar. As a rule, IWM minis are of a much lower "complexity", but they also generally have more unique silhouettes, which make them easier to tell apart (with some outliers; Ostroc and Ostsol come immediately to mind).
For vees, honestly, we've got comparatively a ton of the common vee mini now, so I'm less worried about those. IIRC, the group has access to ~8 Schrecks, at least 6 each LRM and SRM carriers, and ~8 Scorpions. If we find ourselves facing more than 2 lances of Schrecks at one time, we've done something horribly wrong and/or have gone back in time to fight the Star League directly.
Aside from confusion on the tabletop, my main issue is that the MWO minis are not at all fun to paint (I have a MWO Atlas and Catapult in 1/285th scale), because of the panel density. There's a TON of fiddly details and panel lines, which mean they'll take quite a bit longer to paint when you're actually doing individual paneling. That's mostly an issue for myself and Bryan, though.