The thing about ballads is that to me they feel pretty story heavy, and with the language barrier and all it can be pretty hard to get into them. Like they can sound great, the MVs are usually really beautiful and all that, but it's much harder to connect with the songs when you don't know most of the story behind them.
Personally I'm not a huge fan of ballads anyway (although there are A LOT of insanely good ones), but drama OSTs usually take the cake just because it's easier to associate the songs with certain scenes, which really add to them in my opinion.