The relevant definition is #7 in Oxford Dictionaries...
so - In the same way; correspondingly.
Thus we can resequence and rephrase OP's example into something like...
Although "the hoodie" wasn't recognised [by that name OR1 as iconic] in the past, the thing itself has always been iconic.
(Where original even if = although = despite the fact that.)
1 Note that syntactically, either interpretation (name or iconic status) is perfectly valid. It's really a matter of opinion which reading you take from it (or indeed, which reading the writer intended).
Note that OP's cited usage is somewhat "dated, formal", and it does rather conflict with the still-common idiomatic usage so-called. Suppose you've suffered a nasty injury while out hiking alone in a remote area, but you've manage to limp in to a tiny hamlet where you meet a man carrying a doctor's medical bag.
I need medical attention! Are you a doctor?
I am called so, yes.
I am so called, yes.
Both the above replies carry the strong implication that the local people think of him as a doctor, even though strictly speaking he doesn't have the relevant formal qualifications. So you can confidently ask him to look at your injured foot.
But - suppose the guy didn't have a medical bag, and the conversation had gone more like...
I need medical attention! Can you help?
There's a so-called doctor living in that house over there.
In that case you might be better advised to keep going and look for someone else to help, because the strong implication is the person living in that house calls himself a doctor, but he is in fact an incompetent charlatan.