Reality has nothing to do with game balance.
It can. Why have crossbows at all? Why do they need a long reload time? Why make them separate from bows at all?
If you have no criteria for determining how a weapon should function, then you can argue for it to function any way imaginable. "Balance" is not criteria. You can eliminate all weapons but daggers and shields and have a "balanced" game.
You cannot use "balance" as an argument for how a weapon should function, because alterations in other areas of the game can "unbalance" the weapon once again, thus making the whole point of your original alteration meaningless.
Realism is a (more or less) set in stone, objective standard to measure changes against. We know from accumulated knowledge that real life has its own balance, and where it is not "fair", limitations can be imposed to ensure all players have a chance to be entertained/empowered. I believe these "balancing" changes should be out of combat limitations, not a distortion of item function itself. Gold cost is a portion of this out of combat balancing action.
The xbow has its place, but not as a no skill requirement ranged weapon to make melee on equal footing with other dedicated ranged weapon users.
That is the entire point of this weapon. It is not a 'crossbow" if it does not function like one.
Gold cost is not an effective balancing tool for a general class of weapons, only for differentiating between lower and upper tier version of that weapon.
Why? The Gold cost, weight cost, and slot cost is already enough for me to refuse a crossbow for my melee chars.
On top of this is the hidden cost of wasting my melee chars potential by dinking around with a crossbow instead of using my melee weapons I'm paying for.
ALSO, if the difficulty of bows and throwing were based on Strength, then more hybrids would use them if their strength was high enough for the choice to be effective. Crossbows do not require much strength to be used, but are slow to reload and expensive.
At a certain strength, it would become more effective to use a cheaper bow than a crossbow. Longbowmen were better than crossbowmen, but required almost lifetime strength training. Ideally, crossbows are good for wealthy chars who lack strength (something like a 4th generation peasant).