Professional organizations have trouble with their revenue models.
The journal publishing business that the ACM and IEEE are in isn't sustainable long term, and drives people away or causes perverse benefit schemes, similar to how newspaper's business models fell apart in the last 10 years.
A better method would be to focus on conferences and community, which is more of the way that Usenix and LOPSA work.
That said, there's some solid stuff in the ACM journals, and their membership fees aren't all that crazy.
I can't wait until the dead tree editions of their publications go away.