In most fights it is not that important. Beam and flight abilities often have more of an impact. And as a party consists of 4, and some other not uncommon classes can have the spell too, I would not decide the choice of the class because of Longstrider.
I don't exactly know what you do mean with "What?", but the Charisma based classes offer good multiclassing abilities and the Warlock is well suited for some high damage builds, like crit builds.
Btw, as Honour mode is the only mode which counts for difficulty discussions, the Warlock has a dramatic advantage over the Ranger from Larian's idea of a toned down Haste.
