D&D 5E Proficiency "Dice": Do you (or have you) use them?

[Charlaquin]

It doesn't feel consistent because it isn't! The player intuition is completely correct in this regard. d20 + d8 is more random than d20 +4. This should be pretty clear.

It’s less consistent on any individual roll. Across many rolls it will produce a slightly higher average result.

 

[Crimson Longinus]

It’s less consistent on any individual roll. Across many rolls it will produce a slightly higher average result.

Yes. More random with slightly higher average. As d20 is already super random, adding even more randomness is really not needed.

 

[77IM]

Randomness almost always favors monsters. Monsters aren't expected to live through the encounter; the best way for them to win is to just hope to get lucky, and more randomness makes that more likely. PCs, on the other hand, are hoping to live to see 20th level, so they'd rather all the math be perfectly smooth and level, because one huge dip can spell disaster.