These ideas are named to honor the person who did much of the grunt work to get them proven/accepted, but we continue to use the name as a convenience.

If you're working with educated people, it's a lot easier to say, "apply DeMorgan," than to say, "why don't you negate the clause, remembering to negate each of the internal clauses, and switching the and's to or's and vice versa."

There exist people who use the names to sound intellectual, and these people are annoying, but just because some people enjoy spouting (in the general public) "obscure" rules and names, that doesn't mean that using such names is without value.