IMHO, images attached to messages are much more useful than in albums — you have to specifically search out the albums to find those, whereas new messages just show up in the forum itself.

As for resizing them before uploading: if you use a phone or tablet, chances are you can choose to upload a smaller version in the screen where you select the images you want to upload. At least on an iPhone or iPad, anyway —see here for details (it works slightly differently in modern iOS, but the basics are the same).