I think of it this way: in Teamfortress 2, the Soldier class is literally described as "a good class for beginners and easy to play." That doesn't mean that they're a Noob class. There are tons of good Soldier players, same goes for Warlocks. You could say that Self Res is a crutch, but it's not. It's an ability that balances out the class, because it makes up for Glide and crappy looking armor.