I guess I just don't understand why you're proposing this hypothesis and not another.

I can only propose hypotheses I think of.

Is is just the analogy with pica, on the level of "akrasia is a craving to do or not-do X, so maybe its cause is doing or not-doing some unrelated Y"? Does this explain/retrodict some known facts about akrasia that I missed? Or is it just a direction of investigation for now?

It's mostly just a direction of investigation, based on a known thing the brain can do - when some Y is is needed, the brain is known to sometimes ask for unrelated X, which does not eliminate the root problem (need for Y). I'm saying that Tetris et. al. may be the Y in a pattern like this.