A bonus proficiency would be in order I guess. A bonus language maybe too. On the other hand, Int checks are much more common than you may think. I mean, knowledge checks can lurk everywhere.
I don't find knowledge checks especially useful, honestly. I think it takes a lot of effort on the part of the DM to purposefully add in uses for knowledge checks, and unfortunately, they've removed a lot of cool ones. Like knowledge of masonry used to actually be really useful if you wanted to destroy a building, or just avoid being destroyed by a building, and that's just sorta gone. What's left is pretty much three checks that are almost entirely to find monster weaknesses and abilities that I feel you don't really need to know immediately, and one check for world lore (which is sometimes pretty useful still during RP).
I think intelligence does have meaning. Even if you put aside those classes that are pretty dependant on it, how important is it that you play your PC intelligently? So it's either important for mechanical reasons, or becuase that's what you want to play. What other reason is there? If you don't need it for class based reasons, and you don't care about having a smart PC, those are really the only reasons that matter. You don't need to have additional rules complexities to warrant needing it for everyone else outside of those two reasons.
Not every attribute has to be important to every class. Been that way for 40 years; don't see it changing any time soon. Nor a need to.
Except, objectively, this particular statistic used to be more important for non-int-primary classes. That was removed, and now it has nothing. And even then, just because it's been that way for 40 years doesn't mean it's good. Can we really call even 3.5 "good"? Fun to play, sure, but it's completely riddled with flaws by most people's standards. I don't think we can ever say that every attribute is going to be equally useful for every class, but as it is there are very few (if any, for some classes) reasons to not use a 15/15/15/8/8/8 array. In fact, I would say that with how stats are arranged now, with power flattened and all the BAB and buffs and whatnot removed, attributes are more important than ever before to attempt to max out. Yet they have also become much harder to come by, potentially taking all five of your also much rarer feats to reach 20 in just one or two. Taking anything but a 14 or 15 in your important statistics (whatever those happen to be for your class) can be pretty crippling, 'cause you're always gonna be starved for modifiers.
And I think that's actually the big difference between now and then. Rather than int losing uses (which it did), the uses it had became less important relative to your other options. Even looking at it the other way, as a wizard in 3.5, you probably didn't want a strength of 8 because you'd barely be able to carry your spellbook, much less anything else. But now, it's a lot harder to justify putting anything into strength when dex, con, and int are all very important. It's the scarcity of attributes that makes this a problem compared to earlier editions, on top of int in particular also losing relevance.
In my game I have slightly changed rules as written to use Int Investigation checks to find traps and hidden doors. In my opinion, Wisdom Perception measures how fine-tuned a character's senses are without the need for specialized knowledge. But there are somethings that you would never notice without a specialized knowledge of the subject -- you just wouldn't know what to look for. And I rule that traps and secret doors are constructed in such a way that you wouldn't notice them unless you knew something about traps or secret doors and how they are made, so it's an intelligence roll.
I've found that this really balances out Int. and Wis. ability checks. The example I often use to explain it is that to notice footprints on the ground requires (Wis) perception; to know how many there were and how much they weigh and what race of creature they are requires (Int) investigation; and to track them to where they were going or coming from requires (Wis) survival or nature.
I think that could be major enough to warrant use, yeah. It would at least be as important as wisdom and charisma are to a martial class at that point.
I'd probably accept that as long as it didn't happen too often. If it started becoming a pattern I'd just ask them to make Intelligence checks. Honestly, when I'm a player, I'll make checks for my own character if they have low Intelligence or Wisdom and I'm not sure they would have thought of the idea that I just did.
In my book, role-playing low stats is part of the fun the game. In point buy, I allow my players to sell down their stats lower than 8 for good role-playing purposes.
What exactly counts as a "brilliant plan"? Like what plans do your guys' players even come up with? I think the most clever thing I've seen from my players was pushing rocks on a giant centipede as it left its hole. They sometimes plan to retreat. Could you give me some examples of complex plans that players aren't allowed to come up with?
