Là means "here/then/in that case/so" in this sentence. Removing it wouldn’t change the overall meaning.

Note also that before n’était, s’il is implicit and possibly just missing (s’il n’était un élément crucial).

Here is my attempt to express the first part of this sentence in English:

So that would be a depressing statement…

Your translation were it not for a crucial element is right. Not sure about the register of were it not… in English but n’était.. sounds unusually formal to my ears.

Interestingly you answered your own question when you wrote "emphasis added" because this is exactly what the role of "là" is in this context: emphasis.

I disagree with jilliagre when they say this is "très soutenu". Using "là" sounds pedantic or even rural to me because of the redundancy it introduces, as in "au jour d’aujourd’hui". The rest of the text is, pardon me, ridiculous enough to question its seriousness.

"Ce serait un constat déprimant" is enough because "ce" already points to the object. "Ce serait là un constat déprimant" refers to the same object twice.

Or even three times if one counts the word constat.

And this way of repeating multiple times is not super classy French language. Quite the opposite. It is pretending to have depth with shallow words and formulas.

One could be satisfied with a bare "Ce serait déprimant, n’était un élément crucial" (if we are to keep the rest of the sentence intact).