Most of the time I'm just not in the mood to have big foam cups over my ears/on my head.
You can/do hear more "detail" with headphones (unless you have very good speakers and put them on very loud) and great headphones are awesome, but I'd disagree that they always sound better. Different people have different ears....I've yet to listen to any headphones that produce the kind of bass I truly desire. You just can't get that in headphone-size. We used to have these 16" subwoofer (or maybe a little bigger, I can't remember now) speakers on the TV, and movies/games would shake the floor with the bass. That's what I prefer. ... alas, I don't have that kind of gear hooked up to my PC these days.
People do have different ears, yes. But a better sound system will always sound better. The differences in people's hearing only applies to high end audio equipment. People who don't know too much about audio like to use that argument, but if you become an audiophile (yes, its a real thing), you'll learn why its a complete fallacy unless applied to top end stuff. The only time different personal preference
begins to apply to headphones, for example, is at about the $400 mark. Before that the better ones just
are better.
As for bass, yes, you can. With a good soundcard that has an amplifier (mine does), and good mixer software. You can't shake the floor, obviously, but the thing is - the frequencies that are causing that you can't actually hear anyway. The human ear doesn't hear all the range of most subwoofers. There's a reason they're called subwoofers, a true subwoofer is actually silent (because they produce ultra-low frequencies designed to shake the room, and they're very, very uncommon). You can only hear a frequency that is so low, getting the floor shaking will seem bigger but it's not actually going any lower. Headphone drivers can easily manage those frequencies. And you can make good headphones go plenty loud to cause serious hearing damage without damaging them. So volume and frequency are both covered. Shaking a room however, obviously you can't do that, and its completely unnecessary.
As for talking about them being uncomfortable, that's way too much of a generalisation. It entirely depends on the individual model. Quality headphones can be extremely comfortable. Some block out all outside noise, some you can hear everything as if you're not wearing anything.
I always have my headphones on when at my computer, it never bothers me because they're good quality. They are sooooo much more precise than most speakers. ie; when I played competitive FPS, you have to use headphones, because then you can hear exactly where someone is when they're running, to a degree of accuracy that isn't possible with headphones.
You may not have heard what you like from headphones, but I doubt you've heard many quality headphones.
Point being, I don't think you've heard all they have to give, and you shouldn't assume they can't do it... because they certainly can.