You make a good point, but I think there's an important counterpoint to be made. I'm not saying this to disagree, just to express where I'm coming from.
A moderate, safe choice may get elected and stop the kids in cages, and we'll all breathe a sigh in relief (including me). But that person might very well not go far enough, because kids in cages will still be "okay" unless the GOP is held accountable.
This primary has made me really stop and think about what's the most important thing I want accomplished with this election. I realized that while I don't love the notion of our next president being center of the road on policy issues, I could actually live with that if they are committed to helping our democracy heal. And I don't mean mamby pamby appeasement that moderates indulge in. I mean undoing voter suppression tactics, foreign interference in elections, investigating and prosecuting GOP corruption, cleaning up the judiciary, etc. Ultimately, after this shit show, I want to see the GOP annihilated as an organization that carries any political influence whatsoever.
The wrong Democratic candidate will say the right things while campaigning and ultimately accomplish little in office. The ideal candidate will mobilize the entire country around an agenda that will put an end to voter disenfranchisement, restore the rule of law, etc. Of course, nobody's perfect, and none of these candidates are the ideal candidate. To me, the closest to that ideal was Bernie. In November, it will be whoever the Dems put on the ballot. But if it's Joe Biden, I fear we'll have to wait eight years for another chance to heal this thing, and by then, it'll be too late.