There are programmers who love calling themselves "geeks", "nerds", "code monkeys" and promote boot camp style schools as well as myths such as "anybody can code" such that people think any homeless person off the street is a coder.
You don't get doctors and lawyers talking down their own skills or saying it's easy.
So much for being smart and logical, most will never apply this to anything outside of a computer.
And most will turn their noses up at the ethics which would have them converting their technical ability and wealth into long-term power. (To see how this could be done, look at the relationships and rent-seeking behaviour around startup incubators. Others are deftly stealing your lunch.)
The affordance which a software engineer now has will not last forever; power left on the table is power lost. As engineering becomes more commoditised (through education and simpler tools) the pay check will drastically decrease but the less-than positive terms will remain.
It's a personal choice that anybody can make to raise their opinion of themselves, to learn how an executive (and other professions) behave and to not accept less than they are worth. There's so much opportunity to be had. Nobody should be acting like a cog! You should all be playing greater games and constantly redefining what you believe you can do.
A hustler is just a social hacker; a hacker is just a technical hustler. But a human being, they are neither: they are whatever they wish to be.
The second is the cadre of elitist programmers who think they are more intelligent than anybody else, and that therefore if a programmer isn't swimming in money shoved at him by an employer it's because he's not good enough. The egos in the software world dwarf those in the academic world I come from (and that is, believe me, an impressive achievement). Hilariously, it seems to me at least that far more programmers fancy themselves a sort of Programming John Galt (or, perhaps, being a citizen of some Programmer's Lake Woebegon, where all the programmers are above average). They relish competition because they believe, erroneously, that they're working in a meritocracy and that their own skills are so exceptional they will definitely rise to the top anyway.
Doctors/lawyers interact with clients/patients a lot, so they dress to impress; whereas programmers only interact with other programmers or managers, who don't really care. If you're a programmer, the code you write matters much more than the human interaction around it (arguably the same can be said about doctors and lawyers, but a lot of people wouldn't hire a lawyer dressed in jeans and a t-shirt).
Also, there are external dress requirements. For example, a lawyer might get thrown out of court if he/she shows up in casual clothes.
This is the problem half the time. Nerds in childish t-shirts want to sit around pecking out code in isolation instead of taking full responsibility for their work by putting on a jacket and working the organization. This is why IT projects are consistently such disasters and why executives have the idea to get cheap grunts to do this stuff under a layer of middle managers.
The reason that programmers don't dress to impress is that their work product - the value that they add to other people - has nothing to do with their appearance. A programmer is paid for the software she creates; the user of that software has no idea what the programmer who wrote it looks like, and they judge the quality of it by what it does. So programmers have developed other metrics that they use to form a status hierarchy, notably the quality and difficulty of programs that you've written, but also things that are somewhat fuzzier like the technologies and tools you use.
Contrast this with a lawyer or salesman, where your buying decisions are directly influenced by how they present themselves and you often cannot directly determine the quality of their product. People in these professions have a strong incentive to present themselves well because customers have no other information to base their purchasing decisions on.
Certainly in the one metric shared across all professions - money - engineers at top tech companies are not being taken advantage of by management, nor are they "cheap grunts". A senior Google engineer makes more than all than about 2 of the salaries listed on the first page of a GlassDoor CEO search [1].
[1] http://www.glassdoor.com/Salaries/ceo-salary-SRCH_KO0,3.htm
That's completely irrelevant. The point is not whether Google engineers make enough money to be comfortable, or an amount that other people would consider "a lot", or anything like that. The point is that "all" the relevant big tech companies in SV colluded, prisoner's dilemma style, to pay them less than they would have if there were no collusion.
What good does it do anyone aside from the schmoozer and the schmoozee that some middle manager at Apple is good as schmoozing?
However, when groups professionalize in the sense of restricting the supply of people to that job, they are benefiting their own in-group at the expense of society as a whole (customers, employees and shareholders, people excluded from the profession, and indirectly, everyone else). Tech workers intuitively recognize this, and professionalization is the antithesis of hacker culture. In fact, I would say that professionalization wouldn't actually help the nerdy people you are referring to. It would just bring in different people (of course the social justice movement is already working hard to eliminate hacker/nerd culture from the tech industry).
As this article shows, tech workers are fighting this issue through the legal system. Maybe a union will be needed just to deal with this issue. I suspect that the rivalry between Google and Facebook, and the fear of further lawsuits, will keep competition rigorous in the short term.
There are unions for cinematographers and editors in the media. Those are two terribly "nerdy" jobs, and the people who do them are, honestly, huge nerds.
Musicians have a union, and a pension system, and generally do pickup work rather than working for companies. And the musicians in that union are quite a mix of people ranging from "alternative" people (aka, cool nerds) and classical musicians.
Dressing is not important. Business casual is good enough unless you're working in an orchestra. You can be professional in jeans and short sleeved shirts. Most physicians in the ER dress casual.