I'm pretty sure iRacing has thought pretty carefully about the whole "new content vs fix what's already there" thing. iRacing wants to make money, and they seem to have concluded that new content is more important than clutch modelling etc for increasing (and maintaining) its subscriber base. If they'd thought different they would have changed their strategy.
Personally I've got both feet firmly planted in the "fix what's already there" camp, but I realise we're in the minority. Those of us who want brake heating, clutch modelling and engine damage are typically more serious about simracing than the average iRacer. And being more serious about our hobby means we speak with loud voices on forums and such. But we're still in a minority, and that's why iRacing has chosen to ignore our calls so far. From a business point of view it makes perfect sense.