According to the Star Wars: Revenge of the Sith Novelisation, Palpatine went to the Jedi Temple in order to procure the Sith Holocrons that were stored in lowest vaults of the temple.
He would see his friend, his student, his brother, turn and kneel in
front of a black-cloaked Lord of the Sith.
His head rang with a silent scream.
“The traitors have been destroyed, Lord Sidious. And the archives are
secured. Our ancient holocrons are again in the hands of the Sith.”
The Ultimate Star Wars factbook also indicates that Palpatine personally used the Jedi's communications array to send out a signal to lure in any Jedi who'd missed Order 66.
Palpatine also broadcasts a false emergency transmission across space,
notifying distant Jedi that the war is over and instructing them to
return to the temple.
Given that the Emperor subsequently turns the Jedi Temple into his Imperial Palace, it's certainly possible that he wanted to measure up for new curtains and make sure the previous tenant had taken all their crap with them.