...proximity to the financial success of an app makes using 3rd party plugins massively unattractive...
I agree in part. I'm not against using third party plugins per se, because third party devs can actually be great. Ultimate Ads by TobyR is the best ads plugin Ive used for C2, its basically the ad plugin that C2 should have shipped with for all these years. So in that situation where you have a communicative dev maintaining the plugin and providing support I'm more than happy to pay a $ to buy a third party plugin.
But then it can go the other way too, like for a long time people had to rely on the plugins by bloody Cranberrygame for key functionaility (iap and ads) which could be buggy and came with zero support.
It always seemed crazy to me that Scirra would leave such core functionality in the hands of a sketchy, uncommunicative dev like that... It seems like a no brainer for Scirra to own that functionality and bring it under the umbrella of officially maintained plugins to ensure security and ease of use for their user base?
As far as Instant Games is concerned. I hope Scirra can make it clear whether they intend to provide monetisation options in their C3 plugin. Id also be interested to know if they plan to release version for C2, although I assume thats a no since they've previously said thered be no more major feature updates for C2? Maybe they'll share some more info with us soon?