As long as it actually alters the kind of information you get, and the description of how you arrive at it, I'd generally support the use of variant ability checks. They can add interesting and subtle complexity to the game and, if done well, don't need to be misleading or confusing in doing so.
The second post by Ragnarok actually illustrates the concept quite well, and I'd recommend that you consider adding that description and example set into the initial suggestion up top, as it does help illustrate what you're saying.
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Nature, generally speaking
IS an Intelligence check, because usually, what it is being used for, is "What do you know, or what can you recall, or what do your recognise specifically about this thing." That is the purest, truest essence of an Intelligence check.
Similarly, Intimidation absolutely is a Charisma-based skill, because it is about presentation, carriage, presence and force of will... and none of those things have anything to do with the size of your muscles. There are a great many quiet, gentle, softly-spoken and unassuming individuals, who also happen to be a strong and as physically impressive as a mountain... and there are small, cold-eyed, broad-smiling masterminds who can make half a room wet themselves with a couple of well delivered words...
But, the examples given above are exactly the
Right kind of way to handle variant skill checks, and if we had more options like that, that put in the extra work of altering the
kind of information you get and the flavour of
how you get to it, that would be wonderful.
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As for class bonuses and such I'll say this:
A DM at a table might internally set different DCs for different characters, as well as setting different sets of information. This is normal, attentive DMing that helps everyone feel like they're contributing, somewhat prevents the extremely unsatisfying ridiculous check moments, and helps give the people who should have a better shot at doing something a legitimately better chance of contributing meaningfully.
The most common example of this is an adventuring party making Arcana checks to see what they know about a sigil pattern. The DM looks at the group, and, in their mind they might say to themselves:
The Wizard: Has a good background knowledge regardless - they are going to get information pieces A and B regardless, as long as they check... Their DC will be about... 8 to get information piece C, 12 to get information piece D and 15 to get information piece E... and I'll give them some juicy lore-info if they crack 25, because I know they could potentially get that high.
The Bard: Has some background knowledge, but no detailed training... DC 5 to get A and B, 10 to get C, 16 to get D and 21 for E, and their information will be largely the same as the Wizard's, with an allegorical twist.
The Sorcerer: I know they're trained in Arcana, but they operate more in feeling and instinct for the magic, and don't have any academia behind them... They'll get Information piece D automatically if they check. They can't really get information A, not really, but they'll get a variation on B and C if they hit DC 10, and a variation on E if they get DC 17... and if they break 25, they'll get something cool based on the sense and feeling of what's here in front of them.
The Barbarian: No training, but they can check if they want. They can't really get information piece A, but if they hit DC 15 they'll have heard an approximation of information B, and I'll give them colloquial accounts related to C and D if they get 19 (which is their nat 20).
Now, this is the kind of work that a particularly attentive DM does, but even then, it's asking a lot to do that for every single information-based ability check that gets made, and the threads increase again once you start working in variant ability checks as well... However, this is something that a video game can do a variation of, and could do it quite well, potentially.
The main hurdle here, I think, is that we'd be relying on the developers to create a system within their checks and dialogue that can do all this in a way that's satisfying, and present the relevant checks to individual characters – and do so without bogging down the game in a mountain of process-slowing roll. If they wanted to provide every interesting variant ability check that make sense at every interaction point where such checks exist, then in the current system, that would mean that it would need to make a behind-the-scenes (what they call passive checks, which I'm still annoyed about) roll for you, for
Every Single Ability and Variant Ability check present, to determine whether they should present it to you in the following conversation cue... and that's a lot of inefficient processing, so they'd likely want to come up with a better way of doing it, at a raw real-world mechanical level.
The alternative would be to present dialogue options that aren't the and result of what you say (counter to the way it's set up at the moment), so your choices may actually be, first:
1) [Nature(Intelligence)]: Check the plant to see if you recognise it before you answer her.
2) [Nature(Wisdom)]: Observe the plant and see what it tells you about itself before you answer her.
3) “Okay, do your plant thing, I'm ready!”
4) “I don't trust your plant thing, hands off!”
5) [Draw your weapon and attack] (Because this is a Larian game...)
The key thing here being that you only get one of the checks, and because you come at them differently, you may get different types of information on successful checks, depending on which you choose.
