If it was so easy finding new designers that are both willing to learn (lots of) new things, and be able to complete what they started, we would have a way larger team by now.
And that right there is the hard part and probably some of the most successful developers like FSDT, FlyTampa, and Flightbeam work in small groups of only two or three people and have had the same people in place since at or near the time they began.
When you look at other developers like ORBX who are cranking out products left and right with a lot of different people working on things, you start to get a lot of varying results. Some airport look great but perform badly, others dont look as nice but perform great, and then you get the few that look really good and perform well at the same time.
The hard part like you said is getting talented people who will do the things you mentioned, but at the same time if they are really good, they might be more temped to go out and start their own projects or open their own shops.
