It already does, you just dont notice. If you ever hit slew then push the rate up to max and push forward, youll see after a while the game stops to load.
Unlike the GTA where the game is limited to the consoles small amount of onboard memory and buffer capacity. PC's have always got that extra space kept there to avoid the loading screens you get in console games.
I like the idea though, a 5 second loading break would be a small price to pay for better frame rates and graphics, as long as it doesnt come during the short final approach to an airport...