Let’s set the scene you are playing a landfall or a lands matter deck and you need to get more lands into play.
Whether it is the Phylath, the Gitrog Monster, Aesi, Omnath, Omnath, Omnath or even Omnath Landfall and land matters decks want to get as many lands in to play as quickly as possible. Gaea’s touch allows you to play an additional forest on each one of your turns this meaning it can provide ramp as well as additional landfall triggers.
The land having to be a basic forest means that you will have to consider which lands you play as your land for turn and which land you use for the Gaea’s Touch trigger and the composition of your mana base to make sure you can reliably use this ability.
Gaea’s touch also has a second ability where it can sacrifice itself and add 2 green mana to your pool. This means it has functionality in both the early game and late game where it can add additional mana to help cast a ending spell.