The author of the article is missing a negotiation essential to XP, at least: the customer can change his or her mind, but the scheduled tasks are based on developer estimates on how long they will take.

You can't make these estimates with any accuracy without the customer and at least some developers talking. Furthermore, customers aren't likely to pick something that the developers have estimated will take a long time, unless it really is that important to spend that much time on it.

Also, large tasks need to be broken down into smaller tasks to get decent estimates, which means knowing roughly what needs to be done. If the job isn't obvious, something quite like traditional planning needs to happen there.

The planning difference is really for smaller changes that don't have far-reaching consequences.