Why can't the Enterprise be cloaked?

In the original series episode The Enterprise Incident,Kirk and Spock stole a cloaking device from the Romulans.Mr.Scott installed the cloak on the deflector shields and the Enterprise became invisible,allowing the ship and crew to escape the Romulans.So technically it was possible to cloak the Enterprise.In the episode Balance Of Terror,Kirk and crew encountered the Romulans for the first time.Spock was able to track the cloaked Romulan ship on the motion sensor.Spock also stated the power costs of cloaking were enormous.Perhaps the Federation determined cloaking was too draining of a ship's power and was unnecessary since a cloaked ship could still be detected.