It all depends on your point of view. From the IFPI and RIAA point of view modern democracy has developed into economic formula to be manipulated. Corporations spend money to get legislators elected, corporations get closed door access to policy makers, legislators pass laws benefiting those corporations, corporations profit from their investments into legislators.
To IFPI and RIAA, the anti-SOPA and anti-RIAA crowds aren't acting in a manner that fits their democratic reality. The crowds should by their own legislators and let them "compete" with IFPI and RIAA in that way. They can't "compete" if there is single entity to compete against.
"and instituting such a ban is just likely to piss off the very people they're trying to calm down."
The UK lawmakers and government doesn't see a need to calm them down, only to end the riots by defeating them in battle. They are not part of the "us" that the policy makers view themselves as. The rioters are a "them" to be defeated with battlefield tactics. There is no effort to "win the hearts and minds" of the rioters nor to bring them into the circle of "us".
If "they" become part of "us" then "we" become like "them", and that just will not do.
As Abraham put it, "...that this nation, under the Almighty Dollar, shall have a new birth of monopoly -- and that government of the corporations, by the corporations, for the corporations, shall not perish from the earth."