People just pirate instead of making a political statement out of it. Sometimes they justify it in terms of how they're broke anyways, or support creators in other ways, or in terms of how ridiculous copyright law has gotten... but none of it really rises to the level of a significant political movement. Maybe it's the usually toothless enforcement, or the general lack of will to sue 5 year olds for millions over singing happy birthday, or just enough settlement NDAs to hide the lawsuits under the rug, but I guess it just isn't seen as much of a political issue.

I suspect it's seen as a theoretical problem more than a practical one. When specific instances of draconian abuse of IP law do rise to being a visible practical problem (company vs company doesn't count), eventually enough political pressure mounts that one of the parties might fix it. But there are "bigger" issues, so it's usually pretty quiet, with neither party having clean enough hands to score any easy points, so they just settle for not kicking any more puppies.

While copyright reform gets little traction, mucking with the ability to pirate will stir up enough of a hornets nest to actually be a political issue (cough Net neutrality cough), which is currently generally "fixed" by the more regulation-happy Democrats than the business-friendly Republicans.