I don't know about the rest of you, but Strength has always been my dump stat. Strength saves are rare (they are considered a 'lesser' save in terms of class save proficiency value), and strength itself isn't used for much unless you are specifically a strength-based character. It's far easier to dump strength than any other stat, as long as you're not a dedicated weapon-swinger.
Piff has mentioned the streamlining of dependent abilities in 5e - what this generally means is that for your core class, dumping most of your other stats won't hurt you too badly, so the choice of what stat to neglect the most becomes more academic, or personal flavour, at least more-so than it used to be in earlier editions... however, it did crate some obvious trends when it hit actual players. Namely, few people are willing to dump Con, for obvious reasons, and few people are willing to completely neglect wisdom either - Wisdom saves are common and debilitating, and most players want to have a decent perception if they can. Folks are generally less willing to neglect charisma if they can avoid it, since a good deal of D&D involves interacting with NPCs and that's the domain of Charisma. Unless they were a dedicated strength user, and used heavy armour, most people didn't want to neglect Dex entirely either, since dex is a strong save (it's very frequent and is considered a major save in terms on class save proficiency value), and it benefits everyone not wearing heavy armour to some extent. This ended up meaning that the ability scores that people found it easiest to neglect, with the least feeling of cost, were Int, as long as they weren't an Int caster, or Strength, as long as they weren't a Strength combatant.
I would put it out there that and casters should try not to neglect Int too much, even if it isn't their casting score - knowledge checks, and in particular arcana checks, are usually given over to the casters to suss out, after all.
For the casting balances:
Sorcerers and Warlocks are about strength of will and presence of self - that's charisma through and through (no strength of will is not wisdom; common misconception from the save-type transition of earlier editions).
Wizard and Artificer are about precision of knowledge, recollection and application or that knowledge - that's Int.
Druids and clerics are both wisdom, but thy come at the wisdom category from two different sides of the same coin. One is based on instinct, intuition and a sense of the natural flows of power that can be guided and shaped, while the other relies on communion with an aligned entity in harmony (unlike warlocks who are often in antagonistic relationships).
Bard, then, unbalances this scale a bit in favour of another charisma class, certainly (though Lavaeolus is correct in that the fault really lies with the mid-way design decision to change Warlocks to Charisma; I agree with others, it works both ways, depending on the nature of your relationship with your patron), but there are fewer (only one) half-caster charisma classes; Fighter and Rogue are Int-based; they learn academic forms, like a wizard. Ranger follows the styles of druids. Monk's pseudo-casting uses their own ki, which is wisdom based as well, though they're kind of their own situation. This only leaves Barb, who doesn't have a casting line, as of yet, unless you count wild magic (it doesn't really count, but in this instance it uses their Constitution to determine DCs, which is the statement that they deliberately didn't want to tie it to a casting stat.) Paladin is a charisma half-caster, but that's still only one against two for each of the others.
When you take this into consideration, Charisma casters aren't actually overbearing on others by too much - only slightly.
