Int: lore skills
Cha: social skills
So overall, Int and Cha are almost useless except for skills.
You forgot that Int and Cha are useful also for saving throws,
but I think I have a legitimate concern over the designers ability to remember to modify spells which traditionally require a Wis ST to now more or less evenly require Wis, Int or Cha. My fear is that a lot of designers will just not be able to keep this in mind and still convert a lot of spells from previous editions from Will ST to Wis ST, so that we end with Wis be dominantly more useful.
Another possible concern is that lore and social skills are the kind of skills that often
one PC in the group maximises and the other PCs just ignore. Technically, if you have 2 PCs with the same lore skill, your group can check twice on each piece of knowledge, and that's a good benefit (equivalent to advantage) so there is still a reason for multiple PCs to have the same lore skill. But IMXP it often happens that the group reasons like "we have Knowledge X covered already", and this is possibly even more common with social skills. OTOH, perception skills, physical skills, stealth skills and others are useful on an individual basis, which means their relevant abilities are generally more useful across different characters.
Ironically, thanks to the new Skill Mastery changes (which I really dislike), that makes them COMPLETELY useless for a rogue trained in those skills.
I agree...
This is IMHO a problem of the playtesting process as a whole. A vocal minority of the playtesters can come up with a comment or criticism that carries a certain "eureka" vibe, the listening designers think it's a great point that fixes one paradox and stop thinking about the issue because now they have the feeling that the fix is too cool not to take it in. Hopefully they start thinking again about the consequences of such fix...
It's really quite insane that to fix
one small problem (a 1st-level Cleric being better at spotting traps than
some 1st-level Rogues, if such Rogue has a low Wis) that eventually disappears after a few levels, as soon as the skill bonus increases, we have to take a consequence on the entire 'feel' of a character class... because this is exactly that: you
can tell the difference between playing a PC where stat-dumping is easy if not the best choice, and a PC where you have to make trade-offs.