Copy/paste from the manual (page 27):
When you import a stock photo into a print document you get the photo’s full resolution into your design. The resolution of photos varies, but most are much higher than HD resolution.
When you import into a web document, as when importing local photos, the resolution is still limited to HD because it’s rare to need any higher resolution than this for a website.
So any photo I drag and drop into a web document (or import from the Content Catalog) gets optimized to be a maximum of 1920px wide. It's not just a dpi change so it fits nicely on the page, the image really gets reduced to be 1920px wide.

Having full-width graphics on a website is pretty common. Having a photo that needs a lot of cropping is also not that rare.

By already reducing an image on import to 1920px you remove the option to zoom in a decent amount on part of an image and still have it be above 96dpi for the final result. It's even worse if you consider the 2x Retina version that needs to be created as well.

I would really like the option to just drag/drop high resolution images into a web document and not have the program give me a smaller version of it before I've even decided what part of the image I want to use.

Perhaps an extra option under "Options/View" to not automatically reduce images down to HD on web document imports.