Looms dont even turn the tide that much and half the community doesnt even retire so why not
body armor at +3 typically gives you 5 more body and 5 more leg armor, add in +3 gloves and they give you (typically) 5 more body armor. Loomed body/gloves give you 10 more body armor than normal (that is quite significant, at 40 base body armor that's 20% increase).
I notice a huge difference in a +3 heavy lance and a normal heavy lance, you have 1 more speed, and 3 more damage (from 23pierce which is laughable, to 26pierce which is somewhat useful).
Looms do make a difference. Personal skill is still the most important factor, as well as your character's level and build, but looms play an important role.