Even if that weren't a significant barrier, the developers would have to do some work on the code itself to get it ready for public consumption. A while ago, I asked developers what they'd change in their code before releasing it as open source, and half the people who answered the associated poll (admittedly a small sample) said they would do more than minor work: either some code housecleaning so that nobody would snicker at their work or major changes (because of the awareness that others would look at their code). Even if the time to clean up the code to release it as open source is minor, it is non-zero. If it'll help other people, then sure, it's worth the effort. But will anybody care? Is it worth the effort?
Coming up with an answer of "Yes" requires a certain degree of... arrogance? confidence? helpfulness? Some of each, I think. Developers who release their (or in this case their company's) code under the GPL or whatnot have to assume that the code has value to programmers outside their organization. And that's not always easy to judge. Some categories of functionality are no-brainers. It is worth the effort without question if your company developed a better e-commerce module, or features that integrate a well-known open source application with a social network, or a mashup generator, or— well, let's just say that some things are pretty obviously useful.
And some things are just as obviously not useful, such as utilities that reinvented the wheel in colors that matched the corporate logo, or other "functionality" that might be helpful inside your company but make others roll their eyes. (I keep trying to come up with examples of wastes-of-time; perhaps you can suggest a few.) Yet sometimes this code, too, is released as open source. I have to guess that it's done mostly out of kindness and dedication, the spirit that says, "I am committed to open source, and that means I need to contribute back to the community." Which of course is all well and good... assuming anybody cares. And assuming that it's released with a good description of what the software does; I'm sure that you've run across listings saying essentially, "Here's some stuff we did; if you find any of it useful, that's great." Life is too short to paw through open source flea markets even if, hidden in your code, is a snazzy routine that could save the day. I've come to assume, however, that anyone who can't describe what the software does likely can't write a good app, either; if you don't care enough to tell me (the user or developer) what's inside the box, I don't have high expectations about what's in the box.