. Some people just don't like having to engage their enemy in a 3D environment with poor hit detection, I guess.

You're going to experience mechanical complications with any game and that is not a valid excuse to remove jump modules when dropships will still get you on a rooftop. Further more I'd argue that you're more likely to hit a jumper, who has a pre-determined movement path that he CANNOT CHANGE more so than wiggle-strafing scouts and minmatar assaults. When you want to remove all those things from the table then we can talk.

so is it really that they the module+weapon combination is overpowered or a failure to adapt to a changing environment?

Kay, so, argument is going all over the place so I'll try to answer as best I can.

You can adapt to fighting high damage splash weaponry by closing the distance and fighting in areas where they can't jump, or via higher ground yourself. Mass Drivers and plasma cannons are about pointless when your enemy is above you because they have nothing to hit to make use of the splash damage. So, taking a rooftop yourself or being on a hill gives a tactical advantage. You can close the distance, and force them to use their own splash damage against themselves. You can go indoors where they can't jump. Or you can just shoot them while they're stuck on a floating trajectory that they cannot change.

It isn't the responsibility of game designers or the community to tell you how to get that edge, however, so it's largely on you to figure out how you want to counter them.

"Go indoors" is a valid argument against jump mods because if they try to jump they'll hit the ceiling. They can't benefit from their jump mods indoors. But you answered your own question in that vehicles can't follow you inside. To extrapolate on whether or not a player who uses jump mods will follow you inside - I use them and I remain cautious whenever following someone inside. I -know- I can't benefit from my height advantage any longer, I know I can't break their cover indoors, but sometimes I have to roll with the punches and just go with it (maybe there's an objective indoors, for instance). I can always fall back on the heightened melee damage though, and I don't use splash damage weaponry on those suits, so that is a plus.