I think the issue that needs to be addressed is that this situation is similar to buying... a video game perhaps, and getting to a certain point in the story where you find out that you actually have to buy add-on content to be able to continue and this add-on content doesn't even have anything to do with the original story. This is, of course, a concern only in the context of PFS, where chronicle sheets matter.
I feel that including those level gaps is not only an unethical (in my opinion, considering the way these modules are marketed and the popularity of organized play) and unfair way of generating sales, but it breaks up the natural progression of a particular story line to pursue unrelated interests. This is especially true of players who might want to go through one of these scenarios in one sitting.
Again, this is in the context of PFS. With that said, I don't think "providing one level of experience for a much shorter than average play time investment is extraordinarily generous"... is as nearly as generous as the players who support PFS play and continue to purchase these products. We're your customers, and when I buy a module product for PFS play, I don't expect to have to stop players mid-game to run something else so that they can be legal.
We're all thankful for organized play and the money it makes developers, because you continue to put out great products that we all enjoy. I think that needed to be said as well. However, it's still infuriating to see these level gaps. You can make the argument that these modules are 'adapted' for 'society play' and the real product is the module itself, but I don't think that's true. Organized play is what makes money, so if we can fix the level gaps, that would be great. If not, it leaves a pretty bad taste my mouth. Just saying.