No one here speaks for any entire community. In my opinion both factions are very splintered and full of factions that do not interact with each other, either on purpose or by random happenstance. Alliance has the numbers where that splitting doesn’t matter because there are so many people you can’t really tell unless you are plugged into that sort of thing. When Horde RP splinters and factionalizes you can just see it more noticeably because there are less people to hide behind.
As to why people are confrontational and hostile I would imagine it is because they are defensive about what you are implying and thus lashing back. It is the same anytime anyone talks about this topic in anyway on these forums and it will be like that the next time in comes up in a month.
It is a undeniable fact that people prefer random walkup city RP. Thus the large numbers you see of it in SW. We can all be elitist about it and judge people for it and what have you but that changes nothing about how it is the most popular type of RP. Horde simply does not have that as an option on Moon Guard due to a number of reasons some listed here by others and some implied by others here.
As for a sense of community? I don’t think there is an Alliance community or a Horde community. There are various groups, guilds, projects within each faction that are communities, but lets be real they all hate each other so there isn’t any real overarching faction community and working for one is a fool’s errand.