I am a Star Wars Geek. No. Really. I know it's difficult to believe, but its true. And so it was from an early age that I started putting WAY too much thought into things I saw in the Star Wars movies. I have continued to do that throughout the years, and one of the issues I keep coming back to—something that has 'stuck in my craw (kraw?)' for 30 years now (my god, has it been that long?)—is why in the heck did the Rebels use snowspeeders on Hoth.
Now, don't get me wrong. As light patrol craft-specially tuned to Hoth's brutal climate—I totally understand why the Rebellion would use them. But when faced with a full-scale assault by heavily armed (and armored) Imperial AT-AT walkers...why would you send snowspeeders against them when you had X-Wings and Y-Wings. I mean, I don't know how much damage a proton torpedo does (we never actually see one blow up in the movies), but they would HAVE to be better than the small blasters on those Snowspeeders. I suppose you could say that the Alliance was putting all its money on the tow-cable attack thing, but that just seems silly- especially considering the fact that in the battle it only worked ONCE successfully (at least that we saw on camera).
One would have to think that a flight of X-Wings and Y-Wings cruising in low to blast the AT-ATs with Proton torpedoes would have been a hell of a lot more successful. And before anyone says it— the rebels were NOT using all their Starfighters elsewhere. It is shown in the movies that the pilots of the Snowspeeders all had their ships waiting for them on some remote ridge. So...let me get this straight. You leave all of your heavily armed starfighters sitting around while you send a bunch of light patrol craft off to fight the bad guys. It just doesn't make sense. Didn't then. Still doesn't.
Oh, I know the 'real' reason, of course—Lucas wanted to introduce a cool new craft and some awesome visuals of the whole harpoon thing. And the Snowspeeder is a cool design, one of my favorite from any of the movies, in fact. But coolness alone isn't always enough to overcome thinly thought-out reasoning.
So...why DID the rebels use snowspeeders then? Well, over the years, I've come up with a few ways of rationalizing it. Here they are:
1) With the planetary shields activated, perhaps they somehow disrupted the performance of the Starfighters. Obviously shields prevent flying craft from penetrating them, but somehow allow ground-based vehicles to get through- otherwise, I imagine we would have seen a lot of TIE fighters flying along with the AT-ATs. So perhaps the shields also have an effect on flying craft operating beneath them. Since Snowspeeders are low-altitude ships, maybe they were less affected by this. Well, its possible.
2) The Starfighters couldn't operate well in the wet-cold of Hoth's atmosphere. This is probably the strongest argument. After all, in the movies they mention specifically that the Snowspeeders were modified to deal with the cold. Perhaps they hadn't had a chance to modify the starfighters? Or perhaps they couldn't without sacrificing or limiting their ability to operate in space? Putting a little dent into this theory, however, is the fact that Starfighters are clearly able to lift off and fly through the atmosphere with no problems, at least during the daylight and clear weather of the Hoth Attack.
3) The Rebellion REALLY overestimated the ability of the tow-cable attack to be able to stop all the Walkers. I'm not all that convinced about this one. I mean, the Rebels seemed relatively smart, tactics wise. Sure, they were over-matched, but they just don't seem to be the 'put all your eggs in one basket' types.
So, why snowspeeders? Well, in order to help dislodge the stuff stuck in my kraw (craw?), I'm going to say that it was likely a combination of reasons 1 and 2. The Starfighters would have been hampered in their ability to operate in the atmosphere- possibly resulting in a loss of maneuverability/speed that would have made them easy targets for the AT-ATs. Using this rationalization, the Snowspeeders offered the better chance that the pilots would survive.
But then that leaves open the question: Why didn't they mount proton torpedoes on the Snowspeeders? I'll.. leave that one for another day.