I am a fan of Wastrels, but more from a flavour point than in-game effectiveness. McCabe and Lynch are the only 2 crews where I think they warrant serious consideration due to Bravado (McCabe's Upgrades and Lynch's Ace In The Hole), but in Guild I am looking to include them more for body count and the heal that they can bring. The key to making them shine is in learning to use their Cast-offs effectively.
Other reasons I like them are that I can play them as Wastrels, like I don't care; Ruthless doesn't come up every game but is always great when it does. Shooting Manipulative models in the back, ignoring Drinking Contests, hitting Terrifying models. Them and Pistoleros are pretty good Penanggalan hunters. They also don't really care about cover.
And if it takes 3 of the enemy's AP to kill one, then that's just gravy for a 4SS model.