Maybe they should learn a little bit more from it than simply "motivation". Ezra Miller, who actually had a fun a little moment in Suicide Squad as the Flash, told MTV that, basically, the Justice League cast feels solidarity with the embattled Suicide Squad brethren:
You needn't look any further than the Suicide Squad director and cast response to the negative reviews to feel how negative critiques motivate us. Ultimately, we can't base anything on [the critical response]. As artists, we aim to please absolutely everybody with our work, but we also know that we have to keep expressing ourselves as best as we can express ourselves.
Uh, maybe base a few things on the critical response? I'm saying this as someone with the semi-controversial stance that Suicide Squad was an average movie and not a stain on the soul of the world: Definitely learn something from the critical response. Even if it's just "be prepared for the possibility that Warner Bros. will edit your movie in a direction that you never saw coming".
In response to all the hate, Miller added, "It's like that T.I. song, 'Motivation'." That's all well and good, but all the motivation in the world won't actually fix anything if you don't recognise the grander flaws.
Just keep an eye out, guys. If you see something wrong, say something (to borrow a phrase usually meant for keeping an eye out for other kinds of bombs).