I definitely feel both ways about this. When I have a couple of close friends over, I like them to have a place to sit and chat that feels connected to the kitchen. I'm happy to chat and drink with them while I chop vegetables and attend to a pan, and I don't feel too self-conscious about saying "oops, give me a sec" if cooking demands 100% of my attention for a minute or two. And my friends know better than to try to help me with cleanup (though they're welcome to chop.)

When I'm hosting more people, or people I don't know well, I don't want them anywhere near the kitchen. Especially when there are a lot of guests and the kitchen starts to resemble a triage area at a mass casualty event, and when you have to fend off well-meaning people who try to wash the dishes or something else that they don't realize is extremely unhelpful. I need to be on in the kitchen, not sociable. It's work. The kitchen is just for me, my wife, and in extreme cases, close friends who know us well enough to be actually helpful by taking things to the table and replenishing drinks.

The latter situation is much rarer than the former, so I'm glad we have an open kitchen, but I really feel how much better it would be to have a separate room for hosting big events.

I've heard it suggested that the ideal solution would be a closed-off kitchen where you keep all the mess, the simmering pots, the dirty dishes, and the sweat and swearing, and a second open kitchen where you can smile and do the impressive and/or photogenic cooking in front of your guests to show how effortless and organized you are in the kitchen.

EDIT/PS: Space issues are beside the point, IMO — many people living in small spaces have a "dining room" or at least a "dinner table" that is busy with other things the rest of the day (mail, homework, laundry, etc.) and only gets dedicated to meals at mealtime. It's only empty all day if you have a surplus of space.