The ratings were just fine. And they were getting the audience most advertisers lust after; look at the commercials. They were for IBM servers and luxury cars. Those ads were aimed at decision makers and high earners. Advertisers research who watches what very carefully and place their ads accordingly. Those ads were not there by mistake.
I can hear the question: Well, if the ratings were okay, why cancel it?
Because decisions aren't always made rationally or thoughtfully or are even smart. You just have to look at UPN's programming decisions around that time to see that the network was not exactly being run by geniuses. As for not letting SyFy have it, I have no clue why anyone would reject that. Except that I have been told that Les Moonves (head of CBS) absolutely hates SF and hated Enterprise. His actions, such as destroying the sets (which were beautiful pieces of craftsmanship) immediately following the series' cancellation (if not for the one fan who has the bridge set there would be virtually nothing left) speaks volumes.
I admit to prejudice; I loved Enterprise from the start and was (and still am) mystified by the "haters" who used to make it their life's work to denigrate the series at any and every opportunity. You don't like something? Don't ruin it for those who do. I never got the Voyager love, but if you liked it, have at it. (Mind you, my initial enjoyment of The Big Bang Theory is slowly turning into hate watching as Sheldon's character grows from unaware quirky to knowing obnoxiousness, but that's a whole 'nother story.)
Cancellations are part of network television, and I have been trying to figure out why this particular cancellation has bothered me so much. I think it's because of the death of Trip. Poorly constructed, badly written ... I could go on and on, but this thread is not about The Abomination. Offhand, I can't think of another series that ends by killing off a major character in such a god-awful fashion.
There is a movement afoot for a renewal, but I dunno ... Other series have been revived, but I fear that CBS is only in it for the $$$ and they see Enterprise as a losing proposition. I think otherwise, but obviously, they're not listening to me. But still ... the actors have all said they'd come back, and even a mini-series would be cool. The Romulan war would make a heckuva good story, IMO.