Well, it sounds like the current incarnation of the ipaddr module is widely loathed, even if it also has some fans. Since it is still available as a 3rd party module, and hasn't been available in other releases except 3.1 beta and rc1, I expect few users will be inconvenienced if we withdraw it at this point.
Benjamin, what would be involved in removing it? I suppose there's the module itself, some unit tests, and some docs. (I'm not asking you to remove it yet -- but I'm asking to look into the consequences, so that we can be sure to do the right thing before releasing 3.1 final.)
I'm disappointed in the process -- it's as if nobody really reviewed the API until it was released with rc1, and this despite there being a significant discussion about its inclusion and alternatives months ago. (Don't look at me -- I wouldn't recognize a netmask if it bit me in the behind, and I can honestly say that I don't know whether /8 means to look only at the first 8 bits or whether it means to mask off the last 8 bits.)
I hope we can learn from this.