About the only thing I use Maint plans for is backups and CheckDB and even for backups they're not ideal as you can't set some options on the backups (like CheckSum).

They're a poor choice for index and stats maintenance when you have more than a trivial database, rebuilding everything and updating everything sounds great in practice but in reality there often isn't time to do that, plus it's a massive waste of resources. Generally a more targeted index and stats maintenance method should be used.

Good for a novice DBA just getting started