But as a content producer you're not burning stuff onto writable Blu-rays. You're pressing them in a factory at a cost well less than $1 a disc.

Whereas a USB stick, even bought in large volumes, can only be so cheap.

You don't care if memory sticks can grow - you have, say, 20GB of content you want to deliver to your customer. It's just extra cost if you buy a 40GB memory stick to carry it.

I just don't see any incentive (other than marketing/coolness) for distributing anything on a USB stick.

You are correct but you are looking at it from the wrong perspective.

Who cares about reprogramming your stick: for blu-ray, you want to buy a movie. The movie studio is the one wanting to make a profit, so most of the sale price of the movie should not go into the media.

Therefore, mass producing blu-ray movies, at around $1 (or less) per disc is very effective (the studios will sell you the movie at $9.99 or more).

When will a USB stick for 20GB cost less than $1? It's still quite far off.

The assumption, of course, is that you will have 20+gb of content on a Blu-Ray disc. I am not convinced this is often the case, and an independent could produce these slightly-higher-cost items for distribution and put all sorts of material on them.