Gluten is actually the easiest thing for me to avoid; I really feel no craving for wheat products at all (can't say the same about potato chips, ice cream, etc.). I think that's partly because there was one very clear change: the nasty headaches that I used to get every couple weeks just went away. Now I may get one a couple times a year, so it's a stark difference. Those semi-annual ones may be caused by something else (probably stress), or I may inadvertently get glutenized that often. I think it's also helped with sleep, mental fog, energy, heartburn, and a variety of other things, but the headaches were the one clear indicator.
But it's also because it's such a clear poison. When gluten causes problems, it's because it tricks your immune system into attacking your own cells. I damage my cells enough with outside influences; I don't need them killing each other off, thanks. Especially in the brain, which is where we're learning gluten may cause the most havoc.
If I (personally) eat too many carbs, I know my blood sugar will go up, and if I overdo it there could be damage to the pancreas. In the long term, I could end up with full-blown diabetus. But that's treatable; injecting insulin can't be any fun, but people do it and go on living their lives. And it's a relative thing: you have (and require) some blood sugar, and there's a range above that that you can flirt with before causing unusual damage. So it's easy to rationalize to yourself: "Hey, I'll just have a little, and it'll be okay. Hey, I ate this stuff for years, one more time won't kill me. I'll be extra good tomorrow."
But if I eat gluten and my immune system starts attacking my thyroid or hypothalamus, that's not just more of something that was going on normally; that's something different happening. And it's pretty much binary, since gluten acts as a catalyst: either you ate enough gluten to start the auto-immune reaction or you didn't. There's no "oh, it'll just do a little damage" range to play with. Being extra good tomorrow won't necessarily stop the killing.
So that's why I don't find it any harder to pass up the pasta aisle than I would an aisle that said "arsenic and strychnine." Once you see it as a poison for your body, it's much easier to turn down. I wish I could see sugar and vegetable oils the same way (though I'm getting there with the oils).