Personally I prefer the current mixture of shapes but surely the best fix would just to allow people to change app icons, be that to a pack or individually, within the default OS hence giving the choice.
Where do you draw the line though? You will just get people wanting more and more choices. Ex you want one icon pack as a standard option but others want a different icon pack as standard.
Like said above this really isn't an issue. You just find a set of icons you like and then you install them