Why does anyone think that? It's often economically rational for a customer to say "I'd like to continue using your product/service, but I have a specific complaint about it."[1] That's what all these posts about Google+ are doing.
It's not like anyone's shouting "We need to pass laws against this, right now!" Nobody is questioning Google's legal and moral right to force Google+ on us. Rather, people are saying it's a poor choice and Google's part, and it annoys customers.
[1] These issues are discussed in Exit, Voice, and Loyalty:
http://en.wikipedia.org/wiki/Exit,_Voice,_and_Loyalty
The basic idea is that an aggrieved consumer can either take their business elsewhere, which is termed "exit," or try to change the company's behavior through things like the OP's blog post, which is termed "voice." Customers sometimes choose voice as their first recourse, and if things get worse or don't improve, the customers sometimes exit.