Because they are trying to get some of those 100 million EF users to migrate over. Even on a 24MP sensor, some of them using EF-S lenses would still have more megapixels than their nominal camera - and one could argue that 10MP off a full frame sensor is probably better than what the 18MP asp-c sensors could do anyways.Why bring out a bargain basement body when almost all you have are $2k+ lenses? Makes no sense whatsoever.
Also Canon can think ahead to end of this year, and they know what their lenses will be for the next 3-4 years already.
there's only 3-5 really cheap lenses needed;
if canon wants to the next wave would include the trinity of usual primes
24mm F2, 28mm F2.8, 35mm F2.0
after that.. nothing is really necessary.