a lot of the time getting tech 2 is important because it makes sure you have the core skills in that field. ok 5% sheild regen here, or 10% sheild capacity there, or heck 5% powergrid saving over there isnt much on their own, but together they turn your basic missile boat into a powerful sky-fairing vessel that can rip missions to shreds. modules can only do so much if the pilot doesnt have the support skills to back it up.