The reason players stock up on Disadvantages is perhaps the suggested starting value of 100 points is not enough. Biased I may be, but with GURPS characters not improving in their abilities as the game plays on I want to do "really kewl" stuff now. 100 points doesn't allow for that. That's why I liked GURPS Supers. We were given 500 points and the Supers book. I took Disadvantages out of habit by then but not because I needed the points. It was enough to take Gentleman's Code of Honor and such and be all virtue and goody-two shoes like a superhero is supposed to be. Those extra points just went into minor mundane advantage and skills. The 500 points was enough for the superheroic ability scores and powers.

In D&D I like 1st level play. I'm okay with not having "really kewl" stuff now. It is fun leveling up and earning them. With 100 Points GURPS Fantasy, you don't get them now and never get them. Not even magic. You have to "waste" points on Seek spells that do diddly squat. Damage spells are only one die. To get more than one die of damage if you have to spend rounds doing nothing to build it up. I remember once casting Fireball. I spent three rounds doing nothing to get 3d6 damage. The monster was dead by then.