Why is everybody so concerned with the "right" mouse feature?
Is there any reason to not like it (besides animation freking out, of course)? It is too OP for digging you say? Well, it let's you dig faster than with shovel only if you're using stone tools. Speaking of iron/steel tools, you'd want to use shovel over pickaxe for digging sand/snow/whatever anyway.
Faster to dig with it if you have zero stamina? One full stamina hit is actually better than left&right mouse combo with zero stamina, and it conserves your tool's durability pool (which is important, I'd say).
And why would you want to mine something with zero stamina? Well, that's the other story...
"Right" mouse feature let's you actually defend yourself with mining tools - quite a useful thing if you ask me.
Virtually infinite capabilities with combo strikes in close combat! Smashing zombies feels so much smoother with the "right" mouse feature, if you can manage your stamina right, of course:3
If you can't - you're grabbed, bitten and dead - see, Balance!
edit: Though, it is easily exploitable if you have a batch of red bull/coffee))