Nothing complex about generics that the average modern day programmer can't grasp. We're not talking about some '00s enterprise drones that were never exposed to those concepts.
People used to talk like this about closures in Java too -- "too complex, who needs them", etc. Didn't turn out very well for the language's mindshare about the new generation of programmers...
Actually C# already had generics even before the 1.0 .NET release, but they weren't considered stable enough for a 1.0 release and priority was given to other parts of the .NET.
What's the casual definition of complexity? Stuff in here I don't like?
Honestly, in the medal positions for sloppily expressed programming sentiments, complex/simple occupy the bronze/silver positions just behind the ultimate... "elegant".
The complexity was not the issue, CLU, Ada, Eiffel, Sather, Modula-3, ML, and many others lacked the publicity stunt of having a godfather like Google.