It originally just seemed like a weird complaint to me, I think. Like, the reason I love Live at Leeds isn't because of songs like "Happy Jack" and "I'm a Boy." They're just fun bonuses on top of things like "Young Man Blues," "My Generation," and "Magic Bus" where the band stretches out a little more, and the band's sound in this era was different enough to make these alternate versions of some of the common semi-jams interesting (at least to me, as a fan).
I actually hadn't really thought about it from the angle of hearing more Sell Out songs until you put it that way, though. It could've been cool to hear "harder" stage versions of "Our Love Was," "I Can't Reach You," or "Armenia," (or "I Can See for Miles," but they apparently tried and could never make it work). Part of the problem could also be that I've been familiar with parts of the bootleg of this for like seven or eight years, so it's not as much of a surprise or disappointment to see no Sell Out songs; I already knew (mostly) what would be on it, and I'm just happy to see it cleaned up and extended from the bootleg for official release.
I dunno, either way, I'm looking forward to it for what it is.