This is exactly what's happening in my games. So far, it is been quite a while now and I don't think my players would like to go back to normal rolling again.rolling 3 or 4 dice and make the rest even number of dice as average is a nice middle ground.
8d6 would go to 4d6+14 and 9d6 would be 3d6+21
Spell damage scaling in 5e is crap. You get a big jump as you reach level 3 slots (which has always been the case in the various versions of D&D and then you get just a tiny jolt up for every level until you reach 9th where you jump again. That doesn't make any sense, so I reworked all relevant spells after 3rd level for a smooth curve. Finger of Death has been a big victim of this bad scaling (I would rename it to Finger of Damage since it doesn't kill anything at that tier) so it got reworked as well.I like it (I think), we handle crits in similar fashion.
However, it will have the effect of making upcasting more attractive than casting a higher level spell. I mean, why cast finger of death (61 damage avg to on target) when a 7th lvl fireball now causes 60 avg damage to everyone in the area?
In our particular group we use the DMG resting variant where you don't regain hit points on a long rest, only HD, so any spells slots left over at the end of the day usually get turned into healing. I expect even with standard long rest rules it would happen (just not as often) when there is a high likelihood of a fight later in the day and the party is low on HD. After burning the 1st-level slots, all you have left is higher level slots.
Spellcasters in D&D are not intended to be great single target DPS. They are designed for control, utility, and AoE. They gotta have some weakness. I don’t think they need a damage buff.Spell damage scaling in 5e is crap. You get a big jump as you reach level 3 slots (which has always been the case in the various versions of D&D and then you get just a tiny jolt up for every level until you reach 9th where you jump again. That doesn't make any sense, so I reworked all relevant spells after 3rd level for a smooth curve. Finger of Death has been a big victim of this bad scaling (I would rename it to Finger of Damage since it doesn't kill anything at that tier) so it got reworked as well.
I was not talking about upscaling, upscaling is problematic too and never had a good idea to fix it until I encountered this thread. The maximum effect for extra dice is an excellent idea.