I definitely want that, but no skill like "concentration" like in 3e which was an automatic take for any casters, i.e. a boring choice. There needs to remain a very likely chance that kobold will interrupt your spell if he wins initiative. That was the balancing factor that was missing. It feels right, like reloading a crossbow in melee, or standing up from prone would have caused an OA in 3e (I think). But the concentration rules were just kludgy and a mess, you could get it to never-fail levels or it could be never succeed on the other end.
I'm not sure if I want cantrips to be interruptible though, I think they should just go off regardless of whether you take damage beforehand in that round. So it becomes a tactic to resort to cantrips while harrassed and pull out the big guns when / if they ignore the wizard. Bad move, for either Team PC or Team Monster to do that. Having spells merely rely on an attack, every single one (in 4e), only made me think the only solution to every problem was killing it, i.e. the only tool in your toolbox is a hammer, so everything looks like a nail. At that point, tactics become, give me a bigger/better hammer. Bo-ring.
The more I think about it, the more I like the early D&Ds, they really did get a lot right. I am very grateful they seem to be acknowledging that, and building upon it rather than merely spurning it out of a fruitless fixation on modernity. Next appears to be shaping up like a post-modern D&D. Pick the best things from any edition, improve upon them, or come up with new stuff, in whichever way makes for the best game, given "best" is a moving target. At least we can all agree that magic should be distinct from martial, it should be fun and powerful but risky to use, and contain some serious drawbacks and tradeoffs (such as the wizard could easily kill himself or his own party with his spells if used recklessly or thoughlessly). One time our party in AD&D was about to lose the battle to some pirates on a ship, and the pirate captain had some knowledge that would have ended civilization and was on his way to share it, had we not prevented him, it was game over, so I cast fireball, the entire ship sunk, everybody drowned. The end! Or not...the sea elves raised the ship and the pope rezzed us all. The party wasn't too happy with me, but I did the right thing, and the paladins eventually acknowledged that giving up their lives to save the world was a worthy sacrifice. I want D&D to contain possibilities for DM injecting realism, not roadblocks to it. If the rules themselves contain good ways to make magic feel strange, powerful, and deadly, while not all being about reducing enemy HP, D&D Next will have succeeded.