Projectile weapons are sort of a technological dead end - sure, they're powerful and cheap, but you can only research them so far. A Depleted Uranium Cannon V does 40 damage at range 5; compare that with more advanced weapons like Antiproton Beams (50-60 damage at range 8) and Phased Polaron Beams (50-60 shield skipping damage at range 6). Sure, it takes a long time to get to the highest levels of those other weapons, but the fact is they're there and they're reachable, so anyone who doesn't research projectile weapons is probably that much ahead of you toward the other ones!
