DND_Reborn
The High Aldwin
Yeah, I see the game losing some of the risk present at lower levels myself. It is no wonder many games don't make it past 10th level from what I hear.Again, I'm not offering this as a criticism of the approach, since, particularly at higher levels, the game can get too easy. I think the biggest difference would be on save effects, if you're applying it there too. Enemy spellcasters become a lot scarier.
As for casters, it helps PCs as well as hurts them. Consider even a sleep spell. 5d8 normally is 22.5 hp, exploding it is 25.7. That isn't huge jump, but as you know with the skew towards higher totals, makes the spell more useful to PC casters.
As I said in the OP, I am not sold on the idea of exploding things that don't require an attack roll. In some ways, I would love adding it, but in other ways it is daunting.