The trade-off has to do with computability: because (finitely presented) categories can express so much, reasoning about them (for example, the 'word problem' for them) is undecidable. So to use CT as a modeling language requires automated theorem proving techniques, which are computationally expensive, and fast reasoning is a large part of what we're commercializing.

> But the real question is whether it is a _useful_ modeling language for everything.

Category theory is definitely not useful for modeling everything. However, it's useful for modeling a whole lot. Categories have few axoims, and those they do have align well with how humans break down complex problems, so a lot of systems can be modeled neatly with categories. And category models are useful for proving existence, uniqueness, and notions of "maximum" and "minimum" for their "arrows", which are often useful things people try to prove about systems.

I haven't seen any particularly convincing examples of this outside of pure math.