They are not on topic.
This was covered briefly in this question:
Are we about serving, or just cooking/food preparation?
This can become a gray area. However in the context of food presentation I think this is very much on-topic. Again, I'll return to the expert chef example. An expert chef is expected to have food presentation skills. Presentation is essential to a great meal experience. Assuming we do attract experts chefs, they will have this knowledge, and it will provide a benefit to the community. As an example, but not a reason (there's a difference), look at any televised cooking competition or even the penultimate Bocuse d'Or, presentation is very much a part of the judgement of dishes.
However, I'd say we would draw the line at food presentation. I wouldn't consider floral arrangements, tablecloths, or other environmental accessories as appropriate for this site.
Dinnerware, table-setting, etc.
Eh. I don't feel as strongly about this as I have the previous two. This can sort of blend with presentation. I'd say that table-setting is too far out there. However, choice of plate can be tied into presentation. An example is one of my favorite Chicago restaurants Bonsoiree, some of their dishes use unconventional dishes for presentation that really accent and add to the enjoyment of the meal.
I'll clarify some of my opnions regarding the specific topics of food presentation and table setting here.
Proper plating of a dish is expert knowledge that a chef would know, and would find on the curriculum of a culinary school. This is also (almost?) always a major category of judgement in cooking competitions. This should definitely be on topic.
Table setting & Etiquette
I feel more strongly now than my previous answer that this is not an appropriate topic for this site. It falls into the realm of etiquette and just feels too Home & Gardeny -- not our target audience.