I'd wonder again why they were ever fucking around with such limited, inferior projects like the Tyrants and Hunters. I think it might just be the case that Resident Evil is just not what it used to be, which was mostly zombies topped off with mutants and manmade monsters for flavor.
Why is it that all zombie franchises eventually end up not being very good? They start great, but slowly devolve into less and less scary shit. Resident Evil was once the epitome of survival horror, but devolved into an actiony shooter game that focused less and less on making you panic in desperation as you try to survive.
Romero's movies also started getting rather bad with shit like Land of the Dead, which I found so absurdly not-scary that I couldn't believe it was made by the same guy who did Night of the Living Dead. The Walking Dead graphic novels became less and less interesting over time.
I guess, like the zombies themselves, it's just really damn hard to keep the concept fresh. Perhaps that's why RE felt the need to move further and further away from traditional zombies and survival horror over time.
Then again, maybe I'm just a jaded, cynical old shit.