They're inexpensive creatures that don't have a lot of power, but what they lack in strength, they make up for in numbers
We get a better body, too
Naturally this makes lands like Ancient Tomb, Serras Sanctum, and Nykthos, Shrine to Nyx prime tutor targets for a lot of white decks, but if youre trying to find missing colors of mana in multicolor decks, simply being able to snag a Raugrin Triome or Temple Garden can also make the difference between getting off the ground or getting mana screwed
Commander's Sphere is also widely popular for similar reasons: You ramp and fix mana with this rock, and draw a card when needed (for 0 mana, even if tapped out!)
So, if you lose, you can always blame it on the algorithm