Well, the RAM, CLC and PSU's are just re-brands and the cases are their own.
Even if it was all by them, don't really see why its excessive. Not like they can expand much further, I doubt we will be seeing real water cooling stuff from them or anything more focused on the enthusiast than they currently offer.
My issue with Corsair is their sketchy PSU labeling. They started their PSU range with very good brands and priced them accordingly. Now many of the better PSU's they made have been replaced with a different OEM brand which is much cheaper and less reliable but the retail price has stayed the same.
The CX series for example had a 400w Seasonic unit, which was great! Now this is unavailable and they are all made by CWT, which are not worth the retail price. Many of the ax series were made by Seasonic but their replacement axi series is mostly by Flextronics which is not bad but not on par with Seasonic either. The TX Series is split between CWT and Seasonic and the higher rated HX are CWT too i believe. To me it seems like they established good PSU lines at a premium Corsair price but eventually replaced many models under a similar or same name with cheaper internals to get bigger margins.