When most people talk about realism in games they don't mean experience points. But frankly, if you use a gun a long time then you're going to get better at shooting a gun. Same with everything else, the more practice you have with a skill, the better at that skill you become, so yes experience is quite realistic.
That's actually my point. The concept of experience isn't unrealistic, but the way most RPGs handle it has very little basis in real world logic. If one wanted to create a realistic experience system, they would do best to use a system similar to what the Elder Scrolls uses as a base, if you use a skill, you can get better at it, on the other hand, you don't get better at a skill by using a different one. Yet in Fallout, and really, most RPGs I know of, use an experience system where the player has one generic "experience" bar that, after rising by enough points, allows the character to gain a level, at which point you can put points into your various skills, and which skills you can increase is not at all effected by what skills you used while gaining this experience, you could very easily have gained a level from killing enemies yet use the skill points awarded upon gaining a level to increase your skill in sneaking. This makes very little sense if you go by realistic logic, but it's worked since the time of D&D for games.
Honestly, I'd go as far as to say RPGs NEED to be unrealistic to an extent, because an RPG allows the player to develop a character, and allows that character to become more competent through gaining experience, and the game needs to actually show that the experience has made your character stronger in some way, otherwise you get something like Oblivion where gaining levels carries little satisfaction because you don't actually become more powerful compared to your enemies. Now the need for unrealism comes in the fact that, if the gain tries to hard to be realistic, a low level character could still defeat a high level one with one lucky shot, because in real life, no matter how good you are with a gun, a bullet can still kill you. While it would be realistic if a level one character could kill a level twnety one in one hit with a lucky head shot, it wouldn't exactly contribute to the point of an RPG, because it would make the differences in experience between the two characters become quite meaningless, as you can see, what I'm talking about applies primarily in combat, though to a lesser extent, it might apply in other places too, in real life, even a master of stealth is going to have difficulty staying hidden in broad daylight without cover, but if you developed a character who focuses on stealth, you probably wouldn't want to be forced to give up your character's usual methods to survive. In a stealth-based game, the missions can be designed to make stealth a possibility, but an RPG which aims to make all playstyles equally feasible can not always afford to pay so much attention to a particular playstyle. Sometimes, RPGs need to put realistic logic aside in order to ensure that certain character types don't become impossible to play consistently. I would also argue that an RPG does not need to put as much detail into realistically simulating different aspects of it like combat and sneaking and such as games that focus on them because the genre doesn't really focus on them. A first person shooter can put much more focus on realistically simulating combat with guns, because it focuses on that, and doesn't have the burden of needing to account for the different playstyles and character types the player might choose to play. Of course, not all games will actually do this, but that's beside the point.
There is a difference between a realistic setting and realistic physics and natural laws. The former is not important (especially with a good explanation for the setting - Fallout is a wasteland, explanation: nuke war). The latter is very important. A game that does not make sense in physical reality is not fun, imo.
I can only dissagree with that opinion, I've played some games that pay little heed to realistic physics, but are still quite enjoyable, and would actually become less fun if they tried too hard to be realistic, as I've said, it depends on the game. As far as Fallout is concerned, some level of realism is concerned, I mean, I don't want to be able to jump thirty meters into the air or fall safely from a ten story building, I wouldn't really object if the physics of in-game objects at least tried to be realistic, and so on, but loosing any ammunition left in a magazine if I reload before firing off all bullets in it or needing to bathe regularly or suffer a charisma pentalty would just be annoying and unnecessary.
All in all, though, if I wanted full realism in every area, I'd take a walk.
I can, however, say that I too am fine with unrealistic settings, as long as they have, like I said, consistency. Its unrealistic that Fallout's setting goes by '50s science fiction SCIENCE! rather than real world science, but as long as it follows it consistently, I can live with it.