When you write for a magazine with a particular ideological bent, it's natural to wonder whether you're being too soft on "your" side. This question comes up more when your side is actually in power, since they're the ones who are implementing policies and making decisions; when the other side is in charge, most of your time is spent documenting and analyzing all the harmful and dangerous things they're doing, and your side is occupied with fighting the ruling party and waiting for its turn. Obviously, politics is a never-ending conflict, and that conflict can produce a certain siege mentality. For instance, when a Democratic president proposes a plan for universal health coverage and Republicans attack it with a campaign of mind-boggling hysteria and dishonesty (death panels!), it's natural to spend a good deal of time correcting the record and defending it, even if you think that plan is less than ideal. There are some people (like Glenn Greenwald) who write largely about one set of issues, and thus may find themselves regularly criticizing a president from the party they're closer to if that party doesn't live up to the standards they hold, but if you write about a range of issues, most of the time you won't be critical of your side for the simple reason that most of the time you agree with what they're doing.
That doesn't mean that by doing so you've abandoned critical thinking. On health care, for instance, my own position was like that of many liberals who wrote a lot about the issue—that the Affordable Care Act had a number of weaknesses and could have been much better than it was, but nevertheless represented an extraordinary advance that would have a positive impact on millions of lives. Did the second part of that position make us unthinking water-carriers? I don't think so, but Matt Welch of Reason might argue that it does. In an article titled "The Death of Contrarianism," Welch laments that while liberals (and liberal magazines) used to be skeptical of liberalism, in the Obama years they've become little more than a bunch of Democratic party apparatchiks. "The reformist urge to cross-examine Democratic policy ideas," he writes, "has fizzled out precisely at the time when those ideas are both ascendant and as questionable as ever." Welch seems to pine for the time when The New Republic was torpedoing Bill Clinton's attempt at health care reform by publishing the policy con artist Betsy McCaughey and beating the drums for the invasion of Iraq, because that represented a healthy contrarianism.
You should read Ed Kilgore's response to Welch, but I'd point out that contrarianism in and of itself is nothing to be proud of.