Like the OP I have tried most of the engines and cut my teeth on 001 game maker. C2 has the features I use most and I can whip out a the game mechanics in a few hours and then spend my time on the artistic part of the game so speed in design is a major draw for me.
I can't say I need anything C3 has offered but I am sure I will try the free version and maybe something will get me hooked that would over ride my contempt for subscriptions.
One thing that would sway me is the ability to do 3D. The OP says how difficult it would be but 001 has 3D and works fine in HTML5 so Scirra can do it.
I would like to see Scirra focus on getting their arcade server working properly and set up like the store with animated gifs for pics, recommended games, side bar advertising of C2 games and allow designers to use their own pic on the load screen seen on websites instead of the identical Scirra add.
Then we can promote Scirra games and that makes game designers some money so they will flock to Scirra to get the engines.
I think instant gaming with HTML5 will over take apps because people are getting leery of downloading apps that collect personal info and can sell things to kids without parent permission but in order for us to do that with Scirra games they have got to work with websites like mine that need a game pic on the load screen.
Anyway, the OP has their opinion and I have mine and while I hope C3 lives up to the hype and is a good deal for mobile and console game designers I just don't see it being of use to me and it may be a step in the wrong direction of where gaming is going in my opinion.