Would it be proper to say that America is going through a rather formative crisis right now?

it's going through puberty 

Sweetie, That is WAY too proper!  lol

I think it's going through a crisis ... but not so sure it's formative or destructive.  Time will tell.

No ... we won't know whether it is "formative" or "temporary" until a few decades from now.

I would use “unnecessary” to better describe the crisis. 

It's not a crisis, it's a collapse. No culture has ever avoided a collapse after the symptoms began to show. Historians tell us these things are relilably predictable, but details and timing are random. 

Here is an ebook that explains the process: https://comingdarkage.blogspot.com/