If you have been following Cdramas, the past few months there were barely any idol drama until this past July - most of them were war-related drama & modern society. Most of the time, those "war-related/spy & modern society" drama tend to be the highest rating since they are geared towards older generations.
I think you feel that China is airing lots of idol drama because there's more advertising and marketing for them then the other genre...and of course they are from Hunan TV...