Welcome outside your own personal bubble! See, for instance, more or less the first link on the subject from the search engine:
https://www.theatlantic.com/national/archive/2013/06/what-does-american-actually-mean/276999/
You could do your own research if you wished.
On the other hand, weren’t you the one considering the likes of Facebook, YouTube and Twitter the bulwarks of ‘free press’? I suppose that explains the… narrow perspective.
You’d be surprised how much more complicated the world is.
Anyway, back to the topic.
Are you referring to the legendaries?
One week, and two mercs already maxed? Have you thought what happens when most of them are? 
By the way, the renown system is more about that stage of the game — I don’t think you, as a new player, should bother with it much yet (you decide, of course, but that’s just my suggestion, based on my experience).
Do you mean with the same exchange rate as we’ve got now?
You know, I’ve got plenty of excess coins, yet I’ve declined all the trade offers I’ve got so far. One of the mercs, Neeru, levelled up naturally shortly thereafter… There’s Tyrael, but he’s slowly getting there, and Rattlegore, but that’s another story — the rest of my mercs are maxed already. The point is, I see no rush to exchange more coins.
I’d advise strongly against it. Not only is the exchange rate horrible (right now people could use all the renown accumulated from playing the game for about a year actively to max a few legendaries, perhaps… which is not much), but also there’s no rush, I’d say — and more effective ways to level up your mercs, especially for PvE.
At this point, I’m hoarding renown for possible future updates.
Extra portraits are probably how the game should be monetised — after all, they are cosmetic only, do not affect balance, but could be desirable for many. In this light, the second suggestion — yes! I’ve written about it already. Unfortunately, right now you tend to get random occasional offers from the shop — and often not the ones you want anyway.
Yes.
PS
It’s called the bozo worldview, black-and-white, as stated previously — the same one when they cannot possibly comprehend how a bad person could have written a good musical piece, for instance, and if the former was bad, the latter should be burned, discarded and so on (‘cancelled’, if you will), although that’s probably more complicated for them than even to see behind the aforementioned ‘If you’re not with us, you’re against us’ attitude.