One rule, vs a table.Everyone has their own perspective. Not opposed to adding more dice, but how is that any less fiddly than increasing the step? And how is a dynamic add (adding dice based on the die roll) less fiddly than a static die step. I'm not understanding your idea based on reducing "fiddlyness."
What happens with 1d12 and 2d6 ends up siginifcantly changing how 2H weapons balance.
Maybe fiddly is the wrong word. Just a lookup table with significant balance implications that are not easy to fix without adding in yet more subsystems, or punting.
Damage boost is tap based; different PC builds with different tap counts get different boosta that aren't automatically justified in scaling with tap count. Except the designer can punt or pretend it was what they intended, which is what I usually see.
The amount of boost is small per step. I like rules injections to matter and be noticed at the point of application, not just be noted on a character sheet and forgotten. (this is true even if they have larger impact; ie, +1 hit/damage sucks both because it disappears into character sheet math and because it is larger than it looks. A +1 damage effect meanwhile would suck because it disappears; size wise it is small.)
As a DM, interventions onto PC character sheets should be measured. Each one should matter enought hat the gametime spent describing them is "paid for" by their impact, both percieved and actual.
This has small impact (per unit), requires explaination, and then is forgotten about as the PC just uses a different die. It is fiddling with the game, not fiddly in use? If you repeat it (3 steps!) so the impact is significant, the impact is scales with attacks and possible exact weapon types in arbitrary ways.