> 80% of the people only need 20% of the features
Yes, but those 80% all use a different subset of the 20% of features. So if you want to make them all happy, you need to implement 100% of the features.
I see the pattern so often. There is a "needlessly complicated" product. Someone thinks we can make it simpler, we rewrite it/refactor the UI. Super clean and everything. But user X really needs that one feature! Oh and maybe lets implement Y. A few years down the line you are back to having a "needlessly complicated" product.
If you think it could easily be done better, you don't understand the problem domain well enough yet. Real simplicity looks easy but is hard to achieve.