1) I don't understand these people who understimate casual mobile games. If you want to make big desktop game - it's okay. Good luck. But making games cost lots of money (i.e. professional design) and casual games are the best option for begginers. Someone can make casual game -> gets money from ads etc. -> have money for more serious game.
2) Scirra could make some deal with rojohound and add some new plugins in Construct 2.
3) As for now the biggest issue is that both exporters recommended by Scirra - Node-Webkit (PC) and Crosswalk (mobile) are not good for something bigger than simple game. You can make advanced game, but you should be able to play this game without serious issues (i.e. jittering).
4) Fortunetly there is still CocoonJS, so I hope that they will implement native AdMob ads soon.