Berman needed two shows running so that they couldn't push him out.
He was so blind to his waning power that Rick assumed consolidating everything into Enterprise meant that he was sure to make a better show that would translate into Job security from bosses who wanted to destroy him... What consolidation really meant was that he almost had no shows on the air and that his superiors could soon fire him.
It's like when you're playing one of those old games where you don't respawn 50 thousand times, how it doesn't mean that you are necessarily going to play better just because you've wasted and shredded all your other lives. Nothing is going to change that you are an idiot who is going to hang himself in the same way who needs... Did Berman really think that Voyager was only less beloved than DS9 because DS9 was made by superior craftspeople, and that if Enterprise wasan only child it would suddenly be the only fish in a small pond? yes, I said it. Dude was jealous. DS9 numbers plus Voyager numbers = Enterprise Numbers. I mean what are the stupid DS9 people going to do? Wag off and watch Battlestar Galcitica?
If when Enterprise failed, there was already a second show still running in parallel beside Enterprise, it would have cushioned Berman and saved his job and they wouldn't have been able to stop Rick from starting to tool for a new series to replace Enterprise for sheer terror of how he might tank the 10s of millions of dollars of their money he was already juggling, if they piss him off while he's still in control of a Star Trek program and midwifing a second.
(I say this as if Berman had any power to make these choices when he was most probably only a fraction less fates bitch like everybodyelse.)