It is true that Republican presidencies over time will accomplish somewhat more in a world where legislation can pass with 50 votes. They won’t pass nothing, forever. The question is whether a system that makes passing big laws extraordinarily difficult is better either for American government in general or the Democratic Party in particular. The United States already has more veto points in its system than almost any other major democracy, even without adding a supermajority requirement. In the long run, progressive ideas have done more to shape the face of American government than conservative ones. If you wiped off 50, or 100, or 150 years of legislative change, you’d eliminate far more progressive reforms than conservative ones.
A system that makes major legislation almost impossible is not ideologically neutral. It’s conservative. This is why Republicans are perfectly happy to give up whatever limited chances they might have to pass non-fiscal legislation with their majorities in order to inhibit Democrats. Most of what Republicans want to do — confirm judges, cut taxes, defund entitlements — can already be done with a majority.
Would a potential President Biden actually cripple his own administration in order to curtail a future Republican one? Probably not.