As a freelancing platform, Amazon's Mechanical Turk is easy to malign. There are countless microtasks there, and many of them only pay $0.01. Of course, some of those tasks are easy, ala "Boobs or no boobs?" image moderation for message boards. In the realm of writing, however, there are a lot of tasks that grossly underpay and undervalue writers. Take, for instance, requests for 1000 word articles that only pay $2 or less.
Of course, mTurk really isn't the culprit, here. It's only the third party marketplace. The people undervaluing work are the people posting jobs there. It's a lot like faulting a newspaper for posting classifieds for services. Those classifieds are paid for, and the newspaper takes no responsibility (to an extent) for the want ads posted there.
However, the true answer for mTurk is this: in order to make it lucrative, you have to know how to find jobs you can do quickly and that pay well (collectively). This includes taking umpteen qualification tests. Even more, it comes down to effective searching too. So much of today's net reality hinges on finding and using the right keywords while searching. In many cases, I've always found that using actionable verbs are usually better for finding work.
Still, I haven't found a way to break even 5$ an hour. So, the platform is more of a hobby than true worksite, for me, at least.