I think you're onto something. The tradeoff like that is really interesting, since it would even add some real MP management back in. It wouldn't be incredibly punishing to have a ~1.5x delay GCD, for most levels of play, in case someone used them at a bad time and needed to react with a big followup heal.

I think cards still need (a better) rework under this, because otherwise the button setup for the draw slot will be hard to sort out for a lot of levels (going off how much I already hear of people using macros for cards on each slot). I'm not sure that this many Play buttons for single target can really be addressed.