Also the fragility of the Tie Fighters serves as a reminder to the Imperial Pilots that they must obey. Its kind of hard to defect in a Tie fighter when you can't really run away and you can't land on your own. By eliminating hyperdrives and landing gear in the fighters, they had to dock with the Star Destroyer. And since they were pretty cheap to build, it was no great loss to leave one behind if they Star Destroyer had to leave in a hurry. By reinforcing that the individuals are all cogs within the machine, the Empire was able to keep its own troops in line.
I agree with some of the earlier comments though. I don't really see that the empire had a great need to put out fires, so to speak. Their rule was pretty well established and they would have been only fighting disbursed rebel groups, not major Separatist groups across thousands of star systems. So its unlikely that they would have sent in a group of just Tie fighters (why send in a Tie fighter, when you can send in an Impstar-Deuce and a whole wing of fighters). Its not like they were short of Star Destroyers.
Lastly, I think its in the novelization of Revenge of the Sith, but Obi Wan marvels at how handy it is that Grievous' ship had an internal hyperdrive, clearly a luxury in a ship that small, at that time. Saved him from looking for a hyperspace ring, and let him make a clean get away from Utupau.
So I think Tie Hyperspace boxes would have been unnecessary for the Empire and would have actually run counter to some of their policies.