Means testing:
It makes monetary sense ONLY if your remove morality. Contribution to SS is forced by law. In other words the government is going to take my money regardless of my personal desire (except for certain specific occupations that are exempt). Thye are taking that money under the promise that they will return it to me some day (presumably because I can not be trusted to take care of myself). If they (the government) instead looks at me and says "Sorry, you have too much money now we aren't going to give you your money back" That is called theft when done by anyone else, and is a crime.
Contribution limits:
The contribution is capped, but so is the eventual pay-out. If you want to remove the contribution limit, go for it, but you have to remove the disbursement limit as well, otherwise you are just stealing money. Mathematically, SS can't handle the increased pay-out so there is no "fair" argument for eliminating the contribution limit.