I can see why that might be a good idea.
I've seen forums screwed up by wide pictures.
Makes you scroll several screens to the right to see all the text in that thread/page.
On the old forum, you had thumbnails which solved that problem.
Clicking on them provided the user with an arbitrarily wide image in a different browser.
Seems like a desirable feature to restore/enforce.
People sometimes get a little thoughtless posting their pictures, and giving control back to the viewer would be preferable.
Cuts down on server bandwidth, and visitor bandwidth, too.