Nope, they aren't compelled nor is it addictive because once you have completed it, you just stop. Addiction implies a effort/reward pattern that continuously re-enforces the behaviour, but if once you have completed all your T5 engineering and have nothing left to engineer and therefore no longer do engineering, then that's not addiction, because you have stopped, right? If it was addictive then you would continue to do engineering even when you had nothing left to engineer. Really all my T5 engineering isn't complete, but in fact I have some pre-engineered equipment, that....gasp, I never needed to engineer at all, they provided those in part I suspect due to complaints about engineering, to give players a second path to engineered equipment.