My only concern about using 3rd party plugins is that major changes to C2 - like the forthcoming introduction of multiplayer - could break them... and Scirra are forthright in not supporting 3rd party add-ons when it comes to bug fixing. Unless I've missed something they are still not permitted on the Arcade, for example.
If a bug is encountered due to a breaking change in C2 then the rectification work is left to the plug-in author, or the community in their absence. I grant that it probably doesn't happen that frequently, but the next few weeks will be interesting for sure. So, for people like me who don't know more than how to spell javascript, that leaves me feeling that Scirra doesn't support the non-code writer more than superficially.
Scirra sell C2 as a platform that gives non-code-writers the ability to make games and I think it's an excellent tool. However, some of of the juicy and very useful game-making functions, like ad support - the ones you want after you've messed around with making a simple platform game for your mates - are not provided at all and are only indirectly supported through the SDK.
I know this thread is about ad support, so I'll limit my diatribe here... C2 is still the best tool out there for amateur / non-coders to make games, but I do wish that ad support would be formally provided.