Jamelle Bouie asks the question. My point of view is that the liberal mind has certain habits that can't be so easily reversed. The past few decades have not held too many victories for liberals, at least, not as progressive activist types would see them. For example, I would tend to see the welfare reform of the 1990s as a win for liberalism that neutered the issue of welfare abuse, thus setting the stage for a future resurgence of domestic liberalism, but I know from my own personal interactions that many liberals view welfare reform as at best a wash, and perhaps an outright loss. And it's not like there haven't been a lot of tough losses for the left during the last few decades. So, people on the left who are mentally accustomed to losing can easily become the people who can't take yes for an answer, not out of substance so much as out of an inability to adjust outdated thinking so quickly.
This wouldn't be unprecedented, by the way. Some few decades ago, Ronald Reagan's modest but real successes were viewed skeptically by many conservatives who wanted something much more sweeping instead, as this older but memorable post by Daniel Larison notes, and the right at that time was also so used to losing that they couldn't see things in any other terms. I suspect it will take liberals some time to realize that we, too, have won some big battles this past year and a half.
