How useful are professional society memberships? En route to academia, are professional society memberships useful? So far, I feel like I have been paying ~$100/year for a few societies (with student discounts), just to receive copies of their monthly magazines that I only end up skimming over once. I get tons of emails that are vaguely aimed towards keeping people up to date with current research, but one can do that by reading papers anyways. So I don't really see a point to being a member.

Does anybody else feel this way? Are there actual benefits to being a member for societies like these?
In addition to the individual benefits they offer (subscriptions, electronic journal access, discounts, the possibility of distinguished or honorary grades of membership, etc.), professional organizations also contribute to the research community more broadly:


They organize conferences, publish journals, and support other activities, for example in employment, education, outreach, and public awareness.  The academic community would be very different without these services, many of which need financial support.
They represent their field to the outside world, such as government funding agencies, and make the case for its importance.
They intervene in crises.  For example, when the University of Rochester abruptly decided to cancel its graduate program in mathematics in 1995, the American Mathematical Society helped coordinate a very effective response, which led to the program's reinstatement.
They monitor the health of the field and help members address any concerns (for example, by investigating ethical complaints).
They help shape how the field is viewed within academia, through publicity, prizes, leadership positions, invited lectures, etc.


Membership dues help pay for these activities, which are also more effective when the organization represents a large fraction of the field.

Nobody has an obligation to belong to any particular organization, but it's a simple and valuable way to support the field as a whole.  I'd recommend that every grad student join a couple of professional societies.