It may seem crazy to some to not have a cohesive theme, but IMHO, that would have been far more predictable and tedious, than Miranda assembling a small army of enemies, each with their own unique skills. I think it's also designed to panic the player into a "What, now I have to actually FIGHT this chainsaw propeller guy, there's no place to hide anymore!?", state of trepidation.
It gives the game more depth and dimension. Quite honestly, I thought the Soldats in the Factory, the outdoor boss fight with Heisenberg as a huge mech, and the Chris Redfield segment were a much needed change of pace from the Castle and Village parts, and because, of that, I appreciate those early segments more now.
I guess one could argue, but how do Lycans fit in, Miranda and none of her 4 sub bosses have anything to do with them in resemblance? Whether the Lycans fit in with the main family matters not I think, or that there is no warring between the Lycans and Vampires as made popular by some movies. I think they gave adequate explanation that Lycans are formed by a Cadou rejecting it's host, which is a side effect of Miranda's experiments. I mean suspension of disbelief is always part of any horror game, do we really need them to all be the same?
My only real nit pick, but it's a fairly big one, is the annoying subtle aim hitching, which as far as I can tell, is primarily a problem when aiming with mouse. Proper mouse support is something CAPCOM has never taken seriously enough.