I'm a committee person, and this information is indeed public, at least in our state. I can't speak for the D's, but on the R side, these lists are used in setting priorities for door knocking, mailings, and phone calls to get out the vote. Since we don't have any D's registered in the household, we rarely get any of their literature. That's one advantage to the information being public. On the whole I'd rather it were kept private, but these are the times in which we live.
I tend to agree that making this information public seems intrusive. There is much more out there about us that is also intrusive (property records, mortgage information, court proceedings, etc). I've never heard of anything so horrid as what is being described here. It's an abuse of the citizens in my book.