Venture Brothers is pretty much just a bunch of parodies of Johnny Quest and capeshit characters and archetypes, they still made it good.
Overwatch's problem is the characters are pretty much designed to be easily recognizable to identifiable for different languages/countries in a way the TF2 mercs didn't need to be, The old line of blockbuster movies needing to be easily translatable into Mandarin or it doesn't go in? Same shit with OW. EVen with shit like Tracer and 76 being gay, it's quite minor shit that countries where that's a no no, but the gist is the same; super bright, colorful "good guys" fight robots and what pretty much amounts to a team of devils.
They can work it, and I think given what little they've demonstrated I think they can do it easily (PTSD Bastion, DVa not actually being an exceptional individual, etc), they're just lazy. How many characters have super mysterious backstories and motivations now? Sombra, they've never explained why Reaper is running around killing the rest of OW, Doomfist apparently has some plot he killed the old Talon heads to help put into place. Pieces are there, just historically they've been lazy and/or refused to do anything with. But I will concede that even if they did do anything, it wouldn't be but so interesting because of, again, it needing to be Transformers-tier directing in order to be easily translatable and identifiable across borders.
tl;dr There's potential, but it has a ceiling.