that may be the case early on. however, as you level up and such you'll generally get more specialized rather than being a "jack of all trades" as you only have 20 skill points available, but 50 skills to choose from. so specializing into a specific class would be more advantageous in general rather than trying to do all of them.
I wonder how that will affect switching classes. I'm guessing if you're a soldier but you anticipate switching to medic here and there, it would be wise to allot some points to medic skills, because it's not like you get to dole out the 20 points in four different set-ups for each character, right? In other words, you have 20 points to distribute among universal abilities and class specific abilities for each character, and that's it.
If that is the case, then specializing does make sense, though a hybrid of two classes will probably be the most versatile without watering your character down too much. Hopefully it doesn't deter people from switching when duty calls, though.