The "BattleTech - Word of Blake Spectral LAMs" KS was absolutely horrible, it's as if those have never left '98 and never seen a KS before...
No offense to the Iron Wind Crew, but it's obvious that they are oldskool in just about everything and I don't see that changing anytime soon. Reaper was pretty much stuck in the same position until they diversified into plastic, and the Reaper Crew can run a KS...
CAV is it's own thing these days, they do seem to use the same Chinese partners oversees and I suspect that if models were ever produced state-side, Reaper would still do that (the have a machine).
Also keep in mind, plastic isn't one type of material, it's a whole range. Resin is also a plastic for example. What Reaper/CAV uses is a PVC, but in the past it was of a softer kind then their latest batch (the assembled one from their last KS). What Games Workshop uses is a HIPS (plastic). Where a flexible PVC is a bit more forgiving then HIPS with undercuts and the like. Material also doesn't dictate quality, it does give a range of possibilities and limits.
Most of us would prefer a HIPS Mech instead of PVC. An HQ PVC assembled version is a close second, but CAV got that one only right with one mini to date (the one mentioned previously. But when you pay $1.82/Mech and half that for a vehicle, you'll end up with a couple a thousand after a few KS... ;-)
When a company like Dream Pod 9 or like Dreamforge Games can KS plastic model kits for a far smaller Niche then BT, it's not about no market or too expensive, it's a lack of skill and motivation.
What people also seem to forget that, like Catalyst, IWM is a licensor with a limited BT license. It could easily be that they only have a license to produce metal BT minis and plastic isn't covered...
Proxie Models is cool! But keep in mind that he has a very old machine, it's temperamental as hell! And it's more of a hobby then a business for him, it better be, that machine has cost him fingers! Thus an old $5k machine isn't going to produce consistent quality results that you require for a business. That's not even talking about making the molds. Others have tried to get US based manufacturers to make molds, but results have been expensive, of (far) lower quality and often extremely time consuming. Making model kits is a very specialized business. If you don't want to go with China (your best bet btw), you can go with Renedra in the UK. Some others do decent PVC minis...
Also, just starting a KS != money. That also requires skill... Companies like CMoN are experts on that field, also love the quality of their PVC minis. Reaper, while cheap and it scratches that D&D mini itch, isn't the best quality imho. Privateer Press makes both PVC and HIPS kits, their PVC sucks, but their HIPS is excellent! Dreamforge does some next level HIPS stuff, they are currently running a KS for a 28mm Grav tank:
https://www.kickstarter.com/projects/dreamforge-games/dreamforge-games-grav-stug-tank-model-with-stl-filTheir 28mm plastic 'knights' are imho better then the GW versions, moving part, modular weapon arms, etc.
There is a lot of room in plastic mini land, but IWM and imho Catalyst aren't the companies to get you there. Look at what journey and how many years it took to get to the current generation of plastic BT minis, not to mention the pricing on them...