What's the reason why we cannot download
Ubuntu+1 Alpha 1 once
Ubuntu+1 Alpha 2 has been released?
It would be helpful to roughly find out when regressions started to show up (sometimes it's not as easy as simply downgrading one package).
CD images take up a lot of space. Consider all of the combinations of architectures and flavours that one might wish to download. I imagine that the potential use case for this (consider that this method of regression testing would only work for packages on the CD, which are likely to have lots of developer attention anyway) is sufficiently small that it is not deemed to be a worthwhile tradeoff.