Your point being? All of those problems in landing the spell exist with the other spells you plan to nerf.
The thing about Ray of Stupidity is, if your DM isn't an animate pile of shit, dropping its Int score without hitting 0 will still have some effect on how the monster plays. If you don't think high Int is one of the (many) reasons why Dragons are badasses, you Fail At D&D about as hard as a Barbarian who thinks disintegrating anything he charges at by virtue of sheer damage puts him on par with a Wizard.
[EDIT: I do figure I need to be a bit clearer. Dropping the bastard to 1 Int means that, like before, he just charges and attacks, yes. On the other hand, it means that any tactic at all that relies on misdirection is likely to work, which basically means that if you can think in any terms other than numbers, you have Won Anyway. Not to mention that tons of monsters, while not casters, rely on special abilities (and because they're not actually casters, they don't have awesome defenses because they don't get to cherry-pick the nice spells).]
But you know what? Let's ignore that. Because, hilariously enough, the details of how the spell works aren't the point. The point you've consistently failed to address is that not nerfing Ray of Stupidity along with other ability damage spells does not, in any way, make it obvious that low Int monsters are not worth their CR. Your entire justification for treating that spell exceptionally is complete bullshit, because anybody who didn't already know that will instead declare that anything that makes it not so is broken, including Ray of Stupidity.