They tried repeatedly to create alien species that could be used in recurring roles. The Kazon, the Vidiians, the Krenim, the Hirogen, etc. The audience didn't like a single one of them and continually pointed out how it didn't make sense how a constantly moving ship shouldn't have recurring enemies.
What makes you think these robots would work out any better than any of those others? The audience already made it perfectly clear they didn't want any new aliens to begin with.