I think it might depend on where you start. I added the one-button to my already set up action bars. My interrupt was my pinky, as always and easily used. I know where to look for my cooldowns and so on. If I were to start something very new, like a fire mage, I’d not know my spells and I’d be lost.
I swapped out my channeled talents since I’d mash the button and write over them with the next spell, that was easy.
It just takes some thought. Assuming that players who use this feature don’t think is folly.