It's really hard to get people to understand why it's worth investing in metadata and taxonomy projects. The benefits aren't immediate and the reasons can seem esoteric. It's only after the work is done that the usefulness of metadata starts to become clear.
Proof of this comes in this interview with a colleague of mine at REI. This is a quote I’m going to pull out at every metadata and taxonomy meeting from now on:
“[Collecting metadata] turned out to be really smart. We didn't realize the repercussions of it when we did it. But the structured way we captured the meta-data and user-generated content (UGC) laid the groundwork for how we use that content." (My emphasis.)
I had nothing to do with the decision to collect metadata in this instance, but I've seen firsthand the powerful unintended benefits of having robust structured content. Perhaps one way to convince others ahead of time that they should invest in proper content markup is to collect more testimonials and stories like these. If you know of any others, let me know in the comments.