Higher kinded types reduce complexity in the same way generics reduce code complexity. If you think one makes things simpler but not the other, I would assume you're not familiar with it?

Do you have examples of why it would add significant complexity? I use them constantly and it really simplifies my code a lot!

Also, I don't believe 'profunctor optics' is a paper, I think it's just one (interesting) implementation of optics, which are useful in any language that encourages immutability.