Wait I just noticed that... why on earth is Tactician so specific about Range?
Because the card is "tactician", not "easy stress for everyone because stress is awesome". Tactician forces you to use tactics and think about what range you want to be at: at range 1 you get an extra attack die to kill your target faster, at range 2 you do less damage but get to control your target's next move, and at range 3 you get even less damage but have better defense against return fire. Each of these options has its own advantages and disadvantages, and choosing the right one for the situation depends on player skill.
My guess was because both factions can use it. If it had been rebel only, it would have been anywhere on the board, and 5 stress tokens.
Let's not lose all perspective here. The rebel stress abilities aren't that good. The torps are a one-shot weapon, and the stress droid is a unique upgrade that can only go on ships that don't have very impressive stress-clearing options to deal with the stress you give yourself. A fairly cheap crew upgrade that gives out unconditional stress on every attack is way beyond anything FFG has done.