Players have tried, captain. Wants to sink this ship at the helm, alone.
I'm not sure that is a fair statement.
I don't always agree with Hitech on every issue, but in my experience, he will accept outside help where is is feasible and where it won't cost him more effort than it will save him.
He allows player made sounds.
He allows player made skins.
He allows player made terrains.
He allows player made AI missions.
He allows player run Special Events.
Player made aircraft models would probably be a whole other level of difficulty.
First that level of 3-d modeling is hard. It would be a rare skillset. Not every skinner or map maker is going to jump in a be able to be productive.
Models probably have deep couplings to the control and damage logic.
There could be security concerns with letting players that deep into the product.
HTC isn't big on detailed documentation, so just communicating the requirements could be a huge effort for the rare individuals that could actually help.
I believe HTC used a specific model format from a commercial simulation package. (The name escapes me at the moment.) It's more than just the mesh. It's the whole sub-object component model and hierarchy. It's an expensive, licensed product.
I was just joking with Nefarious. I'm not against adding any aircraft. I'm sure that he and the heroes on the Scenario Team would make great use out of any aircraft they ask for.
But I always have said that of all the things we can ask to be added or changed, new aircraft probably represent one of the worst bang for the buck examples. We already have quite a few aircraft in the hangar and most are never flown. Adding one more is a lot of work and isn't going to add much. It might get used in a scenario occasionally. It will get flown a couple of times when it first comes out. Then it will sit in the hangar and collect dust with the others.
But a Dornier Do 17 would be nice too. Jus sayin.

$0.02.