The style of the first temples is much grander than what you'll see today. The church was small and members, but the members wanted to make big sacrifices to show their commitment to God.

The Salt Lake temple took 40 years to complete.

As the Church expanded outside of Utah, the temples were still monuments to the faith, so they kept building impressive temples.

I think they incorporated more symbolism into the early temples. For instance, the first temple in Provo (there are now two) represents the cloud that guided Moses and the Children of Israel.