Without relitigating Russia, obstruction arose out of that debacle. Media went on endlessly about something that was shown not to be true, as did politicians on the left, and many are still ardently convinced of it despite neutral conclusions to the contrary. So while I'll credit your obstruction argument (though I disagree), that grew out of something that was, in large part, baseless.
I'm biased obviously, but my impression is that the general public consensus is that the Democrats were going to bring us to this moment regardless of the significance of the impropriety, and that what has ultimately gotten us here just isn't of much interest to them. And I think that's true. Basically, I think it's likely true the motives are corrupt even if the underpinnings of impeachment have merit.