So you don't like any games that don't have leveling? The primary motivation to play any game should be the gameplay itself, not leveling. Fallout, Planescape Torment and all the other classic RPGs would have been just as great if there was no leveling and you just decided your stats at the start of the game.
Sorry, I disagree.
RPG mechanics are part of the game genre. What you're saying essentially amounts to... oh... that its unrealistic that your full tech tree would be unavailable at the start of an RTS game, so you shouldn't have to first research a Command Post Addon to get Super Assault Troopers. And maybe this is right, but it's still a valid part of the gameplay of a lot of RTS games.
Just like leveling is. A lot of people enjoy leveling up a character. And lets not forget where RPG games come from... They come from the tabletop games. "RPG" in this context does not simply mean behaving like a medic if you happen to be a medic in a game, it implies a whole assortment of baggage that goes along with it... Leveling mechanics in some form (Be they simple leveling up, or more complex skill-and-talent systems) are almost universal among pen-and-paper RPGs, and would be expected from most RPG players if they picked up a game that billed itself as an RPG... Particularly, to use your examples, Fallout and Planescape: Torment... Fallout, for example, being well known to have been "inspired" by GURPS, and Planescape being one of the most widely acclaimed Dungeons and Dragons lines. If I had picked up Planescape and hadn't been able to level my character, it would not be "just as great"... I would have been pissed off at devs for butchering the concept of the game.
Would it have impacted the story? No. Well, not much, it would have in a few places. But the story is only part of the reason I play computer games. If I just wanted a good story, I'd read a book or watch a movie. I play computer games to be entertained, and I find RPGs (leveling mechanics included) entertaining.