You sound institutionalized. Django is indeed awesome for having a ton of features immediately. Of course, once you need to start changing those features you realize you have to dislocate your shoulder to do so.
Django is badass for what it is intended to do: be a kitchen sink. Flask is badass for what it is intended to do: be a platform for composable applications. If you ever need to reason about the internals of your web framework, you want the latter. If you don't, the former is great.
I'm not sure what that even means, but I suspect the thing that disproves it is "The last website I built was in Yesod.". And while it may be in some sense targeted to fill the Django space, at the present time (and certainly at the time I worked in it) it was more like Flask and a couple of things lightly tacked on.
No, my main point is that Django is what Django is, and while that may not be perfect, it isn't useless, it doesn't "suck", it just doesn't meet all needs any more than anything else does. Flask doesn't meet all needs either. Don't complain that water is tasteless when what you wanted was mustard. Being tasteless doesn't make the water suck, it just makes it water. Complaining about its watery nature is just silly.
If Django actually sucked I'd probably not have said anything, but it's more successful at actually bringing together all those things than most of its competition. (Though since there are roughly 1000 web frameworks out there I'm sure there's better things somewhere.)
This was a presentation for a room filled with Django developers that likely use it for just about everything.
The purpose of the talk isn't to bash Django, it was to introduce Django developers to some interesting concepts that are worth exploring and a tool that may suit their needs.
Django is badass for what it is intended to do: be a kitchen sink. Flask is badass for what it is intended to do: be a platform for composable applications. If you ever need to reason about the internals of your web framework, you want the latter. If you don't, the former is great.