FrogReaver
The most respectful and polite poster ever
Pointing out checking on who will benefit from added abilities is a good way to make sure it isn't powering up the wrong characters.
It's also a good way to introduce the general principle that increasing the benefit of any single attribute buffs any class that naturally increases that ability score anyways and to a much greater degree than the characters that dump the stat will feel any such changes you make (unless you just explicitly target the negative modifiers, but then getting the stat to 10 instead of 8 is the new stat dump...)
But, the big point is to make it so characters feel having a low stat, and to carefully consider which stat they dump.
Why though? D&D is a class based game where each class is primarily defined by a small subset of ability scores. Any ability score that isn't one of your primary 3 (or 2 for some classes) is always going to be worse for a given class than one of it's primary ability scores. I mean - Even the "god-stat" dexterity gets dumped on strength based characters with heavy armor. When's the last time you seen the plate wearing PC sporting more than 8 dexterity (10 at the most)? I don't think I've ever seen that happen and dex is arguably the best combat stat in the game.
So getting back to the question - why do you have a problem with a non-int based PC dumping INT? Do you also have a problem with a plate wearing strength character dumping dexterity? Do you also have a problem with the wizard dumping strength?
Intelligence feels like the stat that is easiest to dump because the skills it is associated with are very active and they're very party wide. You only need one person to make that investigation or arcana check.
Or maybe, just maybe - The biggest reasons you see intelligence dumped more are because
1) There's almost no useful multiclass combinations for it - which is one of the biggest drivers for people to take cha, dex, str or wis to 13 (which would be considered not dumping.
2) Your players find cha skills, dex skills and wisdom skills more fun.
I guess my biggest piece of advice, when it comes to avoiding ability scores dumping (if you still find it a worthy goal after some self reflection):
1. Change how you DM skills related to the stat in game
2. Change how characters are created - possibly change to rolling - try lowering character creation ability score maximums - for example you want smarter fighters then make 14 the new starting out 16 - that means 13 is your pre racial stat cap - try adjusting point buy such that buying 14's and 15's costs more than it currently does.