At the time it was pretty obvious to me that Angel was just useless.

That impression was cemented in Prophecy Girl and not lifted until sometime around Reprise.

In Prophecy Girl, we learn that Buffy is never going to get with Xander (NEVER, you hear comics writers?). And we know she is crushing on Angel. But it is human, powerless Xander who initiates the rescue and saves Buffy so that she can save the world. It's like the ultimate thesis of uselessness for Angel.