eh, its not all ALMS fault. The economy has quite a bit to do with it as well. Audi was supposed to run the whole season, which is why they designed the new R15. But cutbacks in the company forced them to withdraw from all but Sebring and LeMans. Peugot had originally planned to run this whole season which would have added another manufacturer to LMP1. And don't forget about Porsche withdrawing factory backing to the spyders because of cutbacks

that would have made the manufacturer count:
LMP1- 4 (Audi (4), Peugot (2), Acura(2), Lola(1))
LMP2- 3 (Porsche (4), Acura (2), Mazda (2))
GT2- 6 (Ferrari (4), Porsche (4), Ford (1), Chevy (2), Dodge (1), Aston Martin (2))

obviously GT1 is basically dead, its been that way for years so I don't even consider it. So if you look past that, it is still a pretty good series. With that breakdown there would have been a 31 car field which is actually pretty decent.