I always thought the reason admin was reluctant to have the forum host the images was perhaps from a legal perspective? I mean all the copyright stuff and challenges that come up storing the data.

But yeah, most forums I have used support direct uploads, and it makes it much easier.

The storage/data-transfer wouldn't be especially expensive, but it's a large feature to add, and then it's a whole new thing that has to be moderated. I wouldn't make something as open as TalkImg, since otherwise after a few years I'd be getting like 10 DMCA takedowns per day which I'd have to figure out some way of processing. It'd have to be somehow a lot more restricted so that the long-term moderation burden wouldn't be too high. I'd rather avoid having to do it at all.