It's kind of a wash, yeah, saving throws do get better and better over time, and being unable to make a saving throw is impossible- but that does relegate a huge swathe of spells to basically being unusable because of "save negates". Ways to impose penalties to saves are few and far between, and ways to get bonuses to saves are plentiful.
Now some might feel this is a good thing, to make casters more balanced, but all it really does is narrow spell choices to those things that can reliably do something in a world of crazy good saving throws on monsters and magic resistance being handed out like candy, lol.
Personally, I think "pass/fail" was a bad system for spells. Degrees of success so that spells have a wider band of possibilities- a bad save can turn you to stone, most people are simply slowed, really resistant ones might take a movement hit, etc..
Illusions, in particular, I think would benefit from such a system, with how well (or not) you save determining how long (if ever) it takes for a creature to realize that the illusion isn't real.