Umbran said:
There is no training for new skills in the Basic rules of which I am aware.
I think of skills in 5e as something like "subability scores" form the old 2e Skills and Powers -- particular aspects of an ability score that you're good at or not, more granularity than "It's just a DEX check!"
Paraxis said:
I am fine with characters using dagger tips to pick locks with disadvantage, or their shield as a drum, random stuff in a pantry as a herbalism kit, stuff like that.
I wonder -- would you also be fine with a character who has "combat proficiency" that lets them deal 1d8 damage with a weapon attack and get an AC of, I dunno, 14, regardless of their actual equipment?
There's certainly a viable D&D in there where no one gives a crap about their equipment spaces on their character sheet (I kind of lean this way myself more often than not). I don't know that I'd put it as "standard," but I'm personally rather fond of the concept.
That said, I think one place where tool proficiencies shine is in getting rid of monolithic ability scores and niches. It lets you do things like play a cleric of a god of thieves and dump Dex without suddenly being incapable of picking a lock or disarming a trap. It also gives the DM flexibility to leverage other ability scores when it's relevant -- sometimes maybe your CON makes you a better lockpicker because you need to maintain concentration. Sometimes maybe your INT helps you figure out the mechanism. Maybe the trap is magical and your CHA helps you convince the bound spirit not to retaliate!
Heck, you could retain that element of tool proficiencies and say, "I don't care if you have the actual tool or not." And other DMs might let them make a check at disadvantage.
For me, a lot of the value is in the division between "this task is something inherent to you that depends directly on one ability score, that those without skill can try" and "this task is something you can't otherwise do, and depends on different ability scores depending on the context."
(Kind of similar to the old distinction between being able to make a check untrained or not)