I've spent thousands of hours in the Creative mode of Minecraft, and I can attest to the fact that my imagination has never been stronger. My hands have built entire cities. They've built ships, towers, castle walls spanning miles, underground mines, railway connections, small towns, hidden enclaves, and plenty more.
However, Minecraft, at its heart, is a multiplayer experience. Building a massive undertaking with a group of friends, or even your significant other, is one of the best feelings in the world. Creative is the game mode to do that in, as you don't have to waste time mining for building supplies and crafting material. You can truly focus on a shared vision or dream.