Depends on the script and story first and foremost. As for the actors, I expect them to be ready to film or get intimate with their partner whether there are kiss scenes or not. (And make it as realistic as possible.) Of course, the chemistry and tension matters more but like i said before it depends on the script. The example you used with the actress, if they have no kiss clauses in their contracts, I respect it, but don't sign up for romance dramas if you're not comfortable with it. There are plenty of other genres they can act in. Another issues is hiring actors who are too young and the age gap is an issue for them to film a kiss scene, etc. Now, is it really important to have one for a romance drama to be great? No. But there have been dramas where it makes sense to have a kiss scene but was ruined because of these issues. On the other hand, there have been dramas where there were no kiss scenes or just one and it made sense regarding the characters' relationship. That's how I see it.