Didn't notice this post first so I already posted same results in a different thread.
I guess it's more of a feature as the docs for LrDevelopPreset do not mention cropping values at all. And you cannot store cropping in user interface presets either.
Have you noticed that every time you addDevelopPreset, the previous preset file will be stored in Trash folder? Few hundred adjustments and there will be few hunder lrtemplate files in Trash. I guess this is one of the reasons why setting develop settings is so slow compared to setting normal metadata items.
Yeah, I'm not sure what makes the crop edge adjustments "special" - I did recently confirm that you can't store them in a UI preset, although you can copy and paste them, and you can change them via xmp and activate the changes that way. Because of the latter, it seems like more of an oversight to me that its not doable via SDK, but I'm just speculating...
Luckily its not a big deal for me so I'm not real "sore" about it, but it does seem like something that should go on the list of things to fix next revision.
Thanks for the heads up about the lrtemplate files and trash.
PS - I've heard complaints about not being able to store crops in a preset on the regular Lightroom forum as well.