Because we want cars.
If you don't want cars you don't have to buy the garage space.
It's a pointless limit that adds nothing more to the game, I haven't fired up GTAO since the hipster update, there is nothing to spend your money on besides ammo and clothing.
I don't care about the clothing like some people don't care about the cars.
It's an arbitrary limit that adds nothing to the game and is simple to remove.
It's not that we want 3 garages, 4 garages, 5 garages, that's besides the point.
The point is that money should be the only limit in the game, not levels, not rockstar, just money : If you want something and you have the cash for it then you should be able to buy it.
People glitched money so there would be no limit? That's not our f*cking problem, that's R*'s problem, and besides, being free to enjoy the world as we please is what was advertised in the previews, as opposed to what we are getting now : Waiting for R* to make the game fun. In the meantime they release dozens of cars we can't store, so we don't buy 'em.
Remove the property ownership limit.