That is happening when installing other sceneries designed for FSX and not DX10 compatible(As i read somewhere). Aparently old sceneries wont work well im P3DV3 and i cant see landing lights in some of them, but FSDT are P3DV3 ready, so..... 
Fact that our installers and all the support software is compatible with P3D V3, doesn't mean the old sceneries are all being remade to be DX10 (and, by extension, DX11, which is what P3D uses) compliant. The only one that we remade for DX10 it's JFK V2, others will follow.
You surely can use all the old sceneries in P3D V3, but not all features will work.
I don't think it might be a good idea to *intentionally* limit the installer to prevent installation into P3D V3, because most of users would still find useful to install an old scenery in P3D V3, which has been purchased when this sim wasn't even on the drawing board.
And, since they are all available in Trial version, new users interested only in P3D V3, can always check the Trial to decide if the missing features are serious enough for them to prevent a purchase.
Full DX10/11 compliancy will eventually come for all our previous sceneries, but it will take time, since we need to work on new products too.
