Obryn
Hero
[MENTION=23935]Nagol[/MENTION] covered it. Basically, even if you pump your stat to max, you still have an issue and fall further behind. The gap just widens less.This is only an issue if you're going to fail to improve upon your weaknesses.
Which is to say, yes, if you dump a stat and don't do anything to pump it up, it will be the point at which you can be reliably attacked by significantly higher-level characters. This is literally a character using their STRONGEST ability against another character's WEAKEST ability.
If that shouldn't almost always (20's excepted) result in the strong character actually having their effect take, I don't know that it would be satisfying at all to play the strong character.
This is the equivalent of a high-level fighter hitting that dude without armor and with an 8 in DEX. Yes, that fighter SHOULD be hitting.
Now, it's important that the effects of hitting aren't over-stated. And given that a lot of suck spells are Concentration, this seems fine. Yes, if your weak point is WIS, you might lose a turn and have to have your friends help you out of a pinch. This is not all that dire of a penalty to face for basically letting your WIS be for crud and expecting to be fine.
I'm now reminded of the famous 4e expertise gap. After publication, players noted that PCs' to-hit and FRW defenses were both too low, ending up in a lot of whiffs on their attacks and unavoidable attacks from monsters.
The original party line was that this was intended, since the PCs will have buffs all over the place. Turned out this wasn't quite right, and didn't make much sense because the d20 wasn't getting any more sides on it, so we ended up with expertise feats and improved defenses.
That's what I'm hoping doesn't happen. I can see making a feat to give you half proficiency on all non-proficient saves. That would pretty much be a "tax" (and a boring one) from what I'm seeing with the math.