Is the Storehouse important in Dragonfire?

Yes. The Storehouse raises your storage capacity: +500,000 per resource at level I.

Two roles:

1. Storage ceiling — beyond it, production is lost/wasted. If your Storehouse is small, you cap out fast and throw away resources overnight.
2. Protection — part of your stored resources is shielded from other players' raids.

➡️ Before launching a big Stronghold tier upgrade (which costs a lot of wood and stone at once), level your Storehouse so you can accumulate the needed amount without overflowing. A quiet building that unlocks your whole construction logistics.