The downside is instead of having an open debate about the pros/cons and having a law with some staying power, the situation changes depending on the whims of whoever is President and who they appoint to various administrative positions.
But that's not because some passive voice nonsense about "political paralysis", it's because these are partisan issues. One party doesn't want these laws to pass, and won't vote for them.
It's not a passive structural problem. There are good guys and bad guys here. If you actually care, it's time to take a stand.
Maybe you could argue that half is below median IQ if you use a bunch of significant digits after the decimal, but I don’t think there are any exams that attempt to measure with such precision.
Partisan issues are not structural problems with the system, they're policy problems with one party. And in my experience people who try to make that argument (and variants, like "both sides do it") are just making excuses to treat the cognitive dissonance of cheering for the bad guys.
 Obvious disclaimer is obvious: not all issues are partisan. There are legitimate complaints to be made about any system of government. Some problems certainly can be structural. This one is not.
Having Mitch be majority leader makes it worse, but you can't solve it by getting rid of him. He's not blocking things because he feels like it; it's his job.