I do not see why it would be attacking the right licenses (i.e., those
authorizing sharing; and the three other freedoms in the case of software) to
share what the law wrongfully prohibits to share. Stallman, author of the GNU
GPL, repeats over and over that "having an unauthorized copy of a proprietary
program is almost as bad as having an authorized copy of this program". He
then explains why "almost": "because, at least, you do not help the one that
purposefully attacked the solidarity of your community by prohibiting
sharing".
I agree that sharing the work of an author who does not want it shared is not
good: you are breaking a contract you implicitly agreed to. In the case of
software, it definitely harms the free software movement because the
predominance of proprietary software makes it hard to switch to free software
(interoperability problems, necessity of a proprietary OS to run the
proprietary applications, etc.). In the case of artistic works, I am not sure
at all.
The objective is the legalization of non-commercial sharing (the only
essential freedom in case of Art). Having most of the people not respecting
the law probably is a good leverage to have the law changed. Four years ago
in France, the majors (with, in particular, the famous "Vivendi-Universal
amendment"), the CD/DVD resellers (the report that led to the law was
directed by the CIO of the FNAC stores) and the private TV channels (the main
one, TF1, even fired employees against the law) made the deputies vote the
HADOPI law. It made a handful condemnations. Just to make examples. Terrible
examples: the first guy condemned was condemned because his wife, whom he was
divorcing, downloaded at his home a song of Rihanna, that she actually bought
but left at her home! In theory, the HADOPI could have condemned most of the
French people to suspensions of their Internet connections. It did not
because that would have made riots! Result: after millions spent in this
stupid HADOPI for virtually nothing (but an infrastructure to monitor the P2P
networks), the law has just been annulled because it was considered
"disproportionate". If most people would have respected the law, it would not
be "disproportionate"!
I used to think, like you, that the law should be respected because it
eventually is the expression of the people (through voting). But, nowadays
(at least), it usually is not the case! HADOPI is a perfect example of how
the law eventually is the expression of powerful businesses. Their interests
rarely are the interests of the people. As a consequence, the law is wrong.
To be heard, the people should do the right thing even if that means
disobeying the wrong laws.