On the contrary - the people you are talking about tend to make up the leadership of what you call to the left disproportianate to the population. I actually agree that you need broader appeal, but the groups you are talking represent about 20% of the population. If you appeal to them at the expense of the population as a whole then you are engaging in the narrowness you condemn. Nurses and medical techs outnumber doctors. Legal secretaries, and para-legals outnumber lawyers.
If fact I think it is the dominance of upper tier of the working class/ middle class (whichever term you prefer) that leads to the freakiness you condemn. Overwhelmingly, as you would expect in capitalism, capital has grown at the expenses of labor. But secondarily, while 80% of the population of the U.S saw their hourly wages drop in the mid-seventies, and never completely recovered, up to 20% of the non-capitalist population has seen their real hourly wage rise. (I say "up to", because if you include stuff like longer commute times and longer waits in markets, and everything coming "easy-to-assemble" instead of pre-assembled, I suspect the actual numbers would be significantly less than 20%). That is a real material interest different from that of the 80%+. And if you look at the left movements, especially key decision makers in left movements, the paid staff, the boards of directors, the major volunteers who give ten or more hours per week, you will find they overwhellmingly come from this caste/class.
That is one reason for the pre-occupation with the exotic. To be crudely materialistic,you can feed ten million starving children at a very low price, but if you want to provide single payer health or build a decent transit system or fund decent education for everyone, you will probably have to change our tax structure. If you are in that top 20%, and socially liberal,and not quite empty-headed or hard-hearted enough to be a Randian libertarian, a really tempting position is social liberalism combined with supporting relief for the agony of the poorest of the poor, without paying much attention to the vast part of the working class who is getting by, never missing a meal, with stable jobs and homes, but who have to work more hours for the same money, have health insurance that may not cover them if they really get sick, whose kids will have a hell of a time getting into college, and who are one minor catatrophe from ending up poor.
(In fairness human sympathy is another motive. For example I have often criticized the tendency of the single payer movement to emphasize the poorest of the poor the uninsured, rather than the affects of our horrible system on people with supposedly "respectable" insurance. But you have horrible, heartbreaking stories that you hear when in that movement, and while some of them have happened to people with decent insurance many more do occur to those with none. In general the people you describe as "exotic" are among the most victimized. )
There really is a middle class (or middle caste if that terminology offends you). They are 20% or less of the population, and their dominance is what is wrong with modern left movements.
Incidentally, one argument often made for middle class in the sense I am using it (not the Marxian one) being a caste rather than a class, is that it is very easy to fall out of that middle class into the working class or even poverty - as has happened to a lot of computer techs.
But the middle class in the classic Marxian sense is the least stable class too. Members of the class between labor and capital always have to fear falling back into the working class, and also have a much better chance than working class people of accumulating enough surplus to become true capitalists. I actually do think treating it as a class rather than a caste is practically more useful in organizing and analytically clearer too. Via Robin Hood's barn, I think I have actually taken a stab at answering part of Ravi's question.