Calling it a "controversy" is, perhaps, pushing it; this I agree with.
But people object to such implementation because said implementations operate on all sorts of nasty psychological hooks and often have ugly in-game side-effects (usually in the form of very grindy mechanics). I'll concede that for an accurate assessment we'll need to wait till the changes go live, but I don't think I've ever seen an implementation of a premium currency that:
a) wasn't "in your face" (think ads or displaying the currency front and center when it's not the main game currency)
b) was transparent in terms of pricing
c) didn't involve a price hike
d) didn't increase grind (especially if gaining such currency is possible via in-game activities)
Pretty much all implementations come with some of the above, if not all. Now, most people don't really object to this in F2P games (the ol' "developers need to make money" argument stands in that case), but it's really ugly when implemented in full-priced games.
I, personally, object to these types of practices in fully priced games. Be these loot-boxes, premium currencies or in-game stores. I sort of gave ED a pass on the in-game store, as that was before the industry went all-in with these things and I wasn't as defensive about it, plus it was a simple "pay X, get Y" type of deal (even if the value was incredibly bad... like "gold horse armor" bad). Nowadays I refuse to purchase (i.e. full-price) games with micro-transactions in them in any shape or form - I play games to chill and have fun, not to have an extra ad running in the background asking for money.
Final note: for a small note on what kind of psychological tricks companies employ I suggest watching the following video:
It's downright chilling. It's not a hit-piece, it's just a conference talk where one developer gives some insight into how to monetize games for maximum effectiveness. These tricks are primarily employed by free games (mobile at that), but there's nothing stopping companies from using the very same things in full-priced PC titles...