On the one hand, after the close call on their renewal last year, I could see that UPN really didn't want them to go on. Paramount's incentives to see it continue were protrayed by the sceptical as a desire to see it reach a stage where it could go to DVD and syndication release.
That is not to say that Manny Cato and the new creative staff of Enterprise gave anything less than their best. They have gained near-universal critical praise for what they have done with the show in the last season. It is this great improvement in quality that makes the decision by UPN to cancel seem so unfair. Obviously they have been guided in this by purely commercial considerations