ahh, you want new 3d models, not textures.
Well, i guess that is a little less work for HTC than adding new aircraft, cos it doesn't need a new flight model, etc. However, for the person doing the 3D modelling it's pretty much the same amount of work whether they're updating an old aircraft or making an entirely new one. Therefore I can see why it's more appealing all round to add new aircraft. The whines seem to be a little louder for that as well.
(In the meantime, reskinning could make a big difference to some of the ugly ducklings, and it is something the community can do.)