The ability system is great for aliens because while it enhances higher life forms, it allows skulks to customize their life form and try out different play styles.
But if you aren't the best at combat, you can still play gorge, which has a massively different set of experiences available to it.
Marines have weapon and armor upgrades. They may fit well into the metagame, but they don't really diversify marine play. The welder also doesn't change marine gameplay, it just allows them to ALSO weld stuff. They are still most useful shooting and building stuff, but you also get this extra ability on the side (that is still secondary to your first two goals).
New players sit on skulk/ar all game. Either because they keep losing their investments, or because they don't want to invite extra complexity into their game (they are still learning SO much, they don't want to be bothered with learning lerk as well). It's nice to have those stat boosts on marines, but you're losing the enjoyment a player gets out of choosing their load out, deciding their play style, executing it, then trying out a new one, all within the comfort of a low responsibility, low risk marine.
But if you aren't the best at combat, you can still play gorge, which has a massively different set of experiences available to it.
Marines have weapon and armor upgrades. They may fit well into the metagame, but they don't really diversify marine play. The welder also doesn't change marine gameplay, it just allows them to ALSO weld stuff. They are still most useful shooting and building stuff, but you also get this extra ability on the side (that is still secondary to your first two goals).
New players sit on skulk/ar all game. Either because they keep losing their investments, or because they don't want to invite extra complexity into their game (they are still learning SO much, they don't want to be bothered with learning lerk as well). It's nice to have those stat boosts on marines, but you're losing the enjoyment a player gets out of choosing their load out, deciding their play style, executing it, then trying out a new one, all within the comfort of a low responsibility, low risk marine.