I can defend writing for low pay or even for free in some cases. Just remember: even if you're not getting paid, you're still likely to be read - so the writing matters.
Case in point: a website offering the (unpaid) opinions of self-appointed human resources experts. Some sound pretty smart. All are using the site to increase their visibility and presumably get new clients. But I wonder who would hire the one whose bio states he's proud of "restraining himself from beating the crap out of bad managers and employees" and who, in his spare time, enjoys telling "stories about his co-workers with friends over a beer after work."
The bottom line: think before you publish.