I often find that I have no recollection of the tutorial after I've done it (usually because I am annoyed that it has come up when I've probably downloaded the app because I need it now).

I think there's room for both, but I think it's nuts to assume that the people who really do need a walkthrough will:

a) Remember it

b) Be able to find out where to get the tutorial again, unless there's a giant "?" button at the top.

I think your vision is skewed, if all you require is "a quick bit of intro text". I've seen tutorials that are minutes long, and it's just awful.