Most definitely! I had a date with a lovely guy and we got on well. But at the end of the night when he kissed me, it was awful!! Really sloppy & tongue darting out all over the place at the weirdest moments. Completely put me off him, sadly!
Great kissing, for me, can be important. Its the first peek into sexual chemistry. An explosive first kiss will leave me desiring more. a relationship lasts because it's with someone you share common grounds with. It lasts with someone you can enjoy being around Saturday night, or Tuesday morning. Sexuality is a good jumping off point, but there should be so much more.
You could practice at it if it isn't just right but some people will never get it right, if after some practice it isn't great then I believe it's time to say good-bye. So yes, I do feel it is essential to a relationship. A lot of people think the eyes are the most important feature they look at, I say it is all about the lips. I look at someone's lips and wonder if I would want to kiss them.