I suppose that's the interesting dilemma about crossbows. They're more difficult to make and require a well developed culture to invent, but they're easier to learn. Bows are simple to make and most, if not all, hunter-gatherer cultures have developed some form of them.
I imagine large cultures with an emphasis on numbers (like peasant levvies) would find them more useful than smaller cultures, like wood elves relying on a warrior-elite.
As for elves, yes, they do tend to be awfully boring on their own. There are interesting things to do with them, particularly the wilder part of their origin. Perhaps taking a few notes from the Celts would work? Wild, unpredictable forest dwellers, as opposed to really pretty people singing songs.
A full-on dragon culture would be amusing to see sometime, with various breeds for different purposes. It's a common trope, but they're usually not the core of the culture.
That is true, come to think of it. Crossbows were often used in stationary warfare, such as sieges, where the delay didn't matter as much as the marksmanship. Now that you say it, it'd likely be the other way around on field battles; numbers over aim.
The volleyfire from longbows were indeed much more devastating on the whole, but the English had to emphasise archery training among the population in order to produce that many archers. I believe they banned activities like (medieval) football so that it wouldn't take time away from the important archery training. And then muscles come in to it. If you haven't built up the muscle strength, it's rather difficult to fire at range, even if marksmanship isn't a concern. If they couldn't draw the string far enough, it'd fall short.
(Amusingly, this often led to soldiers having great, big muscles on one arm and an ordinary set on the other)
Of course, longbow volleys were still utterly devastating, and no doubt traumatized the surviving French nobility for years after Agincourt. Interestingly, the chivalrous nobility had been rather unhappy with the crossbow when it became common, too, since it had a bit too easy of a time to punch through their then-current armour.
As you say, the real reason bows are most featured in fantasy is because it looks good, and implies alot of training on the part of the character. The only beef I have is when bows is the only ranged weapon of use in an IP (looking at you, Oblivion, at least your little brother got something extra with the DLC).
That's true, I just remembered things like the shortbows used by mounted archers. Hmm, perhaps another trait for the draconic Mongolia-esque culture we drew up for fun earlier?
Dear me, I'm relearning alot I didn't know I'd forgotten.