I think it depends on your target customer base. Most of my models are aimed at the FMCG (fast moving consumer goods) sector. A typical scenario for one of my customers is they are a designer/creative director who needs a model today/tomorrow that's UV unwrapped to match a simple artwork template. They just upload their artwork onto the model & it works right out of the box. They only need basic navigation skills in their 3D app to get what they require. If you compare what they would pay a freelance 3d artist per hour (between $30 to say $70), to what I charge for a model (on average about $40) then they can make a judgement about the best way to go.
You make some very good suggestions, as undercutting leads everyone in a race to the bottom. CGTrader won't make as much commission either. I recently put the prices up of all my models, but applied maximum discount during sales. This way I still keep what I would have been giving away in the discounted price.
There is also the suspicion that a cheap model is either stolen or won't match the image previews. I am always sceptical when I see a model with amazing topology, loads of formats for sale at less than say $10.
I'd send your suggestions to the people in charge at CGTrader, the best thing about this site is that artists are actively involved in making a more prosperous community for everyone.