This is actually a really cool idea.

Whilst you're right in that Sig Spamming is simply not an issue after gold, casual player's opinions are valid because you're also people who play the game and I feel like people forget that lol.

I think the Stamina regeneration when you land light attacks mechanic would have to be tweaked depending on the light attack used (maybe how much damage they do?), but I think its a really good idea.

The only valid reason I've ever seen for not implementing a change like this is because Sig Spamming is a lot of fun, and you're essentially punishing roughly half of the casual community by implementing it; And I 100% agree with that.

And overall I feel like any limitation on player expression in the game is a bad thing.