Captain profession functions as the dodge/evade of space, so it makes sense to skill it like those skills when being shot/attacked at (this was heavily exploited by those who were skilling captain in hogglo diablo ae damage for those who remember - some space players left the game over this when they saw their efforts skilling space skills the hard way(in space) practically nullified)).
Mounted blp/laser are the skills for normal vehicle and stationary weaponry and it makes sense that if they are valid for a quad weapon to be fired in planetside pvp then it should remain the same skill/profession when in space.
Privateer/mothership turrets on the other hand dont exist planetside and it makes sense for them to have their own skill/profession requirement as being the only 'pure' space weaponry.
All of them are easily skillable, now even more then they used to.
Atm gunner skills dont make a dime of a difference anyhow , mindark needs to fix turrets first to actually require skills again lol - everyone shoots the same damage/hitrate on turrets for the last 5 years.