A function in the ACP is added to enable/disable this new functionality. Disabling it would revert the functionality to that in 1.1.5 and earlier. If this isn't possible to implement, then I would propose that this new functionality is removed altogether and is reverted to that in 1.15.
Discussion on this new functionality started here:
The issue with this new functionality is that many users will continue to use the copy and pasting pictures as they have done before with the consequence that forums will end up hosting the images instead of simply linking to them. This has consequences for server space (especially for large forums) as well as copyright - some websites take a very hard line on other sites, including forums, taking and hosting their images, and ultimately it's the forum owners' responsibility not to breach copyright.
Although we can try and educate our users, we won't succeed in at least some cases, especially with the less tech-savvy. Setting permissions to prevent using attachments doesn't solve the issue either as there will be users who do want to upload images that they have on the computer.
Don't get me wrong, I think this new functionality is great. However, I think it's going to cause more problems for forum admins, hence my suggestion of either a control in the ACP to enable/disable this feature or to revert the functionality to what we currently have in 1.1.5.