AD&D "infrared" caused a headache in so many ways (can I see the invisible person's footprints, does hiding behind a rock defeat my vision, etc.). While infrared is more realistic, Darkvision simplifies it much in the way a pair of military grade Night Vision goggles might do. "I see everything, but only to a certain distance similar to my normal vision and only in black & white." It's in no way at all based on physics (night vision tech amplifies some existing light source to make it appear black and white, or greenish, and D&D Darkvision can exist with ZERO light), but it is a simple rule.
With that said, I did like playing the AD&D infrared spectrum. Players looked for ways heat signatures would come into play, and any time players are putting on their thinking caps, the game usually gets better.