Some Transformers have it better than others.
Wheeljack is not one of these Transformers.
I mean, just look at him. He doesn't have any knees, his ridiculous fists can't even hold anything and he looks like some sort of midget robotic gorilla. Sure he has the most firepower of any of the G1 Autobots, but what happens when the kickback from those giant shoulder cannons knocks him onto his back and he can't get up because the idiot who designed him didn't give him any knees? Sure, he could transform, but how annoying would it be to have to transform after every shot because you're too poorly designed to brace yourself? I personally have no experience with being a transforming robot, but I really can't imagine it being all too pleasant.
However, this shouldn't be a problem because Wheeljack's a scientist, right? Well, once again I should note that I don't have any experience with this, but I can't imagine it'd be terribly easy to do any sort of scientific stuff with square, clublike fists that can't hold anything. And why did the pacifist get the biggest guns, anyways? That'd be like if the Dinobot that would become Swoop was afraid of flight. Completely pointless, y'know?
So Wheeljack doesn't catch a whole lot of breaks. But, hey... At least he has a fast vehicle mode. Not that a race-car alt-mode is terribly useful when fighting in the desert, which just happens to be where 90% of the Transformers' battles are fought...