Trivia: The space shuttle Enterprise appears in the title sequence of the show - this shuttle was named after the Enterprise from the original series (after a poll, and also because Star Trek was President Carter's favourite show). A case of reality imitating art and then art imitating that reality.
Trivia: The character of T'Pol was originally going to be T'Pau, the Vulcan high priestess who appears in the original series episode "Amok Time" and in the film Star Trek III: The Search for Spock. Her name was changed because per WGA rules, the scriptwriter who'd written "Amok Time" would have had to be paid a royalty for every episode.
Answer: While ratings did drop, there was a lot going on to cause the rating drops and cancellation. First, "Enterprise" was on UPN, which was dissolved a year after the show was cancelled. At the time of cancellation, it was UPN's highest rated drama. Because they were on at night, they were often preempted by local UPN broadcast of baseball games. And it wasn't even aired in every market. They also lost a major corporate backer early and it was difficult for them to over come that loss. Plus, for season 4, they switched to a Friday night line up, so they were competing against Fox shows, like "The Simpsons" whereas on Wednesdays they didn't have much competition.
Bishop73