I've been lurking a long time, but this discussion got me to finally create an account.
The notion of "originality", in a medium that's 30 years old and with tens (hundreds?) of thousands of titles, is absurd. There are occasional leaps and bounds (innovations), but for the most part, it's a matter of finding (or trying to find) the right combination of elements and mechanics that have already been proven successful.
In ME2,I found the combat system derivative of Freedom Fighters. Multiple other games use the same sort of weapon selection wheel. If the "conversation system" was unique to Mass Effect or Alpha Protocol, all it did was tweak the age old response system of displaying your potential response(s) as complete sentences and you selected one. The Paragon/Renegade system has been reiterated dozens of times, to varying degrees of success, for the past ten years.
Anyway, a driving factor in producing game sequels is to appeal to a fan base that's already established. Madden, Super Mario Bros., Street Fighter, Metal Gear - everyone that buys these games know what to expect. It's just a matter now of tweaking elements in the system to make it better without taking away its strengths.
Complaining about originality is short sighted. It's the formula that matters, now.