The issue with chicken isn't about what observers think about your sandwich. Rabbinic writings (that I will have to come back and cite later, sorry) record ways in which chicken is similar enough to red meat to be subject to the same rules. I do recall that possible confusion was part of the discussion, but as best I recall, that was more about the contents of stews, not intact drumsticks or the like. But the halacha applies regardless of the form the food takes.
Appearances (in general, not just for meat and milk) do matter; there is a halachic concept called marit 'ayin, which is, loosely, giving the wrong (negative) impression. It's because of marit 'ayin that if you serve almond milk with meat, you leave some pieces of almond in. (That's a medieval example.) A modern application is that if you serve those fake "bacon bits" alongside a salad, you do so in the original packaging, not by putting them in a separate bowl. I've seen margarine served with bread in its packaging, to demonstrate that it is not butter.
Proper labeling mitigates confusion caused by either natural similarity (like margarine vs. butter) or intentional imitation (like almond milk or fake bacon bits). We are allowed to eat things that resemble non-kosher items; we're just not allowed to eat actual non-kosher items.
Imitation crabmeat falls into this category. So long as it has a hechsher (kosher certification), meaning it does not contain actual shellfish, it's fine to eat. (Do be warned, though, that many "imitation" crabmeat products do contain some shellfish for flavoring; it's not actual crab but it has crab in it. That's not kosher. Look for the hechsher to be sure.)
