For his avatar, a member may upload or "enter a URL to an online avatar image" (such as photobucket). Why is there no such option for profile images (upload only)?

Yeah, it should support both - I'm sure there's a reason why not....

Security risks, basically..

Besides, you don't have the same control over remotely linked images, and there's very little reason these days with the huge amounts of storage most hosts offer for cheap not to just upload the images to your own server.

Why is it more of a security risk for profile pictures than avatars?

It's not "more" of a risk - the same risk is associated with both. We've/We're considering removing it for avatars as well.

Don't do that! Then nobody would be able to have funky dynamic avatars like mine (it changes when you refresh it).

We know removing the feature for avatars might not go over too well, which is why we didn't do it yet.

It's not "more" of a risk - the same risk is associated with both. We've/We're considering removing it for avatars as well.

So many of the avatars are remotely linked to imageshack, photobucket, and other free sites. This would NOT be a good first for IPB Please don't remove it!

what would happen to existing members that have personal photos externally linked?

[b]what would happen to existing members that have personal photos externally linked?

They get converted and stored locally during the upgrade.