Regarding your first point, which do you suppose is more likely: that love is a bad idea, or that having a very reductionist viewpoint is a bad idea?

Regarding the second, a lot of things are like "the brain chemicals involved in love." (The article only discusses low serotonin levels.) This doesn't provide a basis for thinking love is a bad thing.

Regarding permanence, "is lifelong commitment to a single person a good idea" is a different question from "is love a good idea?" Since you've asked, though, I think I disagree with the mechanics you describe. The benefit of a lifelong love isn't strictly limited to the loved one as an object, or the traits inhering to the loved one, but the interaction between you. This grows over time, while other interactions that you aren't having are likewise not growing.