The points already made are the most valid, is the link there for a good purpose and linking for linking's sake is virtually always a waste of effort.

As far as search engines go, they only want to see voluntary links, in place just for editorial reasons. In reality this may still involve reciprocal links but once these stretch beyond a moderate proportion of links, or to a high number, you put yourself at risk.

Algorithmic devaluation is one possibility and any human review which this might trip is not going to have much sympathy for link exchanging, even if this might to an extent be on subject.