KNOTS would've looked out of place when up against the more "hip" 90210 and MELROSE PLACE. The core cast of KNOTS were only getting older, and had they continued to add younger faces to prolong the ending, we wouldn't've liked that anyway.
It's best KNOTS stopped.
I think this sums it up best. KNOTS had been on the air for 14 solid years, and it remained relatively consistent all the way. Sure, it had a few dips in quality, but never quite the lows of DYNASTY, FALCON CREST, or even DALLAS.
It's a testament to the quality of KNOTS that CBS kept it around two years longer than it kept DALLAS, and that CBS was evidently willing to keep the saga of the cul-de-sac spinning until 1995, pending David Jacobs' approval. But Jacobs knew it was time to hang it up. He didn't want to whimper the show out.