You seem to be misunderstand the situation. The market wants realistic visuals in a lot of games. Therefore, the have a product that'll sell to their audience, some developers don't have the option for cutesy games. Can you make a cartoony shooter? Yes. Can Infinity Ward make a cartoony COD? No, because then it won't be COD. Can you make a cartoony racer? Yes. Can Polyphony Digital make a cartoony GT? No, because then it won't be GT.
Nintendo (at the moment) prioritises games to be family friendly and visually light-hearted, so whatever game they make, they have the option of going cutesy and light-weight on the visuals, but they play to a niche. The whole market can't follow suit and serve that same niche. If every game in 2015 was Nintendo-style cartoony, gamers would be up in arms and developers would struggle to stand out and make sales.
Actually, Borderlands is pretty demanding and performance is lousy (
0fps on PS3 with poor IQ). Cel-shaded isn't really what we're talking about here, but simpler visuals it's easier to hit 60 fps with. Borderlands running at 60 fps on PS3 with clean lines would need a far simpler look - simpler geometry and simpler shaders.
Yes, on paper, but in reality it's not true when you're trying to make a competitive product that sells and your audience likes realistic visuals.