Point being, such "mistakes" continue to this day. Nokia isn't alone in this. (See the HD2)
I'll disagree with you that hope is dead for the N900 simply because there won't be an official MeeGo build for the N900. The hope shifts now to applications, which is the lifeblood for any platform, and that gets a boost with pr1.2 with QT 4.6 and the opening of Ovi Store. With a compatible framework and a commercial store, that opens things up for more applications, potentially. If we didn't have that, I'd have to agree with you.
Considering it seems the average phone user changes devices at least every couple of years, if not more often, I think that's less of an issue than those used to the tablet market.
I don't think it was a bad decision at all. Until they allow me to use a stylus on a capacitive screen, I'll probably never feel comfortable with it. I also prefer a h/w keyboard as well over touch screen.