5e has a lot more options available to every character all the time, I feel like the turn-based format they're rolling with helps players keep up with martials having more abilities that're always on the go, and spellcasters always having an array of cantrips on the go instead of falling back on a crossbow or something when they're out of slots.
They said on the stream they did of the demo that they were initially planning to use the real-time pause style but when they looked at what players would be capable of doing at any one moment, they felt the turn based style (Which isn't as restrictive as you might have thought) is far more suitable for a game adaptation of 5e specifically.
