I don't think the battle for Hoth can be regarded as an example of tactical stupidity by either side. Unless you are willing to make the worst possible assumptions in each case of course
The Imperials.
The mission of the initial ground assault, led by General Veers, was to destroy the Rebel power generator using Walkers.
This would allow a second wave of infantry led by Darth Vader to land and secure the Rebel base.
It is also likly that the Infantry transported by the first assault were used to secure the landing area for the second wave.
The intention was that any rebels who managed to launch their spacecraft would be captured when they reached the blockade.
The case against the Imperials is that they failed to secure the area around the Rebel base, allowing numerous Rebel ships to escape.
This is not a good case; If the Imperials had taken the time to organise and land enough forces to secure the entire area surrounding the rebel base, it would also have given the rebels enough time to evacuate before those forces arrived on the battlefield. It should be remembered that the entire battle was over, and the final evacuation complete, only 10's of minutes after the first Walkers appeared over the horizon.
The Rebels.
The basic rebel evacuation plan is quite good;
A powerful energy field to buy time.
A powerful Ion cannon to knock holes in a blockade.
A ground force with artillary and air support to slow down any ground assault.
The problems they faced is basicly one of time; they had only hours to prepare their defensive lines, while simultaneously trying to pack as much equipment as possible into the transports. They probably always intended that their ground forces would be as strong as the other elements of their defence, but never had time to complete the preparations.
The big questions are always; 'Why didn't they know that their blasters would be useless against the Imperial Walkers?' and 'Why didn't they use their X-wings with the powerful proton torpedoes?'
I would suggest that they DID know that the AT-ATs main armour would be too strong for their blasters, but they hoped to be able to find an exploitable weak-point (which explains why they spent to long firing ineffective blasters at them). If they didn't know it is difficult to explain why Rouge squadron spent time coming up with a desperate backup plan involving harpoon guns and tow cables.
As to the X-wing issue, I'd suggest that their are three possible explanations, which should be considered before falling back on stupidity as the only explaination;
1) The X-wings had some Hoth-specific technical problem which effected their combat systems, but not their basic ability to take off and land.
2) X-wings are actually not very good at low speed and low altitude in an atmosphere, and would never be considered for use in that role. Maybe their repulsorlift system is optimised for simple take-off and landing only, and do not support hard combat maneuvering like a dedicated combat speeder. Also they are much bigger targets then the little speeders.
3) Proton torpedoes may not be ideal weapons for use against mobile ground targets.
