If people though D&D: the movie was bad then they may have not seen other films from the post-D&D sword and sorcery genre. I've chosen a cluster of 7 from around the same time period, some are good - some are so bad they are good.
Hawk the Slayer (1980) A hero assembles the last dwarf, last elf, the last giant and the last man with a repeating crossbow. As corny as it sounds.
Excalibur (1981) About the best film that could be made at the time, with a very dry Merlin and a whole battlefield full of conflict and tragedy.
Dragonslayer (1981) A film that benefited from being no more bizarre than it needed to be. Features some serious crafting sequences ...
The Sword and the Sorcerer (1982) A gimmicky, unwieldy sword is used for the hero to slash his gorey way towards an excessive doom, which for him is doddle.
The Beastmaster (1982) A film where a hero with a set of wild beasts, which appear and disappear when needed, does his thing. The ferrets and the heroine star.
Conan the Barbarian (1982) A film that nearly did the Conan series some good but this was a time when fantasy films had to cheesy. It was compulsory.
Krull (1983) A truly bizarre film where it often seems that it is being made up as it goes along. The even mislabel the central weapon as a "glaive".
Note that watching Excalibur after Monty Python and the Holy Grail is recommended. It is a rather surreal double bill but a very enjoyable one.