Because without the less expensive, less thirsty engines...there would be no V8 for the rest of us, because the car wouldn't exist. The old "muscle car", and even the old "pony car" boundaries are irrelevant today.
Simply put, the Camaro doesn't have the luxury of being a low-volume seller like the Corvette. It MUST sell...and the market has shifted to a group of performance buyers much more tolerant of 4 & 6 cylinders. It just so happens that these engines, combined with lower weight and better aerodynamics also increase fuel economy...and that plays to the companies desire to meet CAFE.
If it performs well (this isn't the 80s, and anyone not living under a rock should be able to accept that a 2.0T lighter Camaro WILL perform well...see ATS, Regal, Cobalt SS Turbo, Sky Redline, etc...)....looks good, and it appeals to the market, why the heck not?
IMVHO - if there's still the V8 option for those who want it (and there will be)...then there's really nothing to complain about.
EDIT: I've said it for the better part of a year now - if you want to see how a xxxxxxxx - Camaro would perform...look no further than the Cadillac ATS. In this case, look at the 2.0T version that everyone's raving about, and that's in a sedan.
