What problem does this address?

Chatting with @mtias @henriqueiamarino and @pablohoneyhoney about the effort of populating the Pattern Directory, it makes sense to also pursue more common layouts, displaying them as wireframes, in addition to more opinionated combinations of image and copy. Because of that, the way the images blocks get displayed is important.

This is the current Image block placeholder:

What is your proposed solution?

For Images (and perhaps Cover and Gallery Blocks), it would be nice to improve the placeholder directly in Gutenberg, perhaps add things like aspect ratio, nicer placeholder drop-zone, etc so we could display it in the directory, instead of adding sample images, as shown below.

It can be relevant to align these placeholders with the ones created for other blocks such as Featured Images.