: What about Halo Anniversary? Yeah, they didn't really make that for the most
: part, but why couldn't they have? What about doing some other in-between
: type game before a full release like Halo 4? What about, I don't know, a
: public beta? They didn't have to have this as their test-bed.

I think Anniversary might have been a later idea, and they were probably already pretty deep into Halo 4 development at that time.

Public betas are more for marketing and building excitement than they are for testing the game. Sure, there's an added bonus of squashing bugs that they wouldn't have noticed otherwise or making small gameplay changes, but it doesn't go much further than that. The differences between the Halo 3 and Reach Beta and final build are pretty minimal. So even if Halo 4 did have a public beta, it wouldn't change much (except maybe the need for small updates).