So what's going on? Are people just pretending to be offended?Short answer: yes, people are just pretending to be offended. That's what's going on.
See a related post from Conor Friedersdorf.
Longer answer: the US has a disconnect between a political system based on parties, bargaining, deal-making, logrolling, and, more broadly, (self-) interested people and groups finding ways to work things out with each other, and a political culture that has quite a bit of disdain for all those things. See, for example, Mr. Smith Goes to Washington, and the dozens of movies and TV shows that have followed, all built around the idea that parties are bad, interest groups are bad, cutting deals is bad, and the only hope for democracy are radically independent people with pure motives who alone have access to what constitutes good policy. Thanks to that disconnect, there are always plenty of perfectly ordinary things that pols do in the perfectly ordinary course of their jobs that can easily be sold to many reporters as corrupt.