When a PLEX is traded, two players benefit. One gets ISK, the other doesn't have to pay for his game time. CCP gets the same amount that it would get if both players paid for a subscription (but may benefit indirectly due to better player retention). When you buy an item from CCP then one player gets an item and CCP gets money.

While I think that's a fairly significant difference, it's not the single big issue that caused the forum rage. There's a lot of accumulated rage from other things CCP have done, many broken promises (including "no microtransactions" just about a year ago, or player-made clothing from earlier Incarna announcements), many years old unfixed bugs, completely broken balance in some areas of the game, the certainty that most of the money you pay them doesn't actually get those bugs fixed in EVE but helps finance two completely different games (they actually told us that, which caused a bit of rage back then), and in fact now we have an "expansion" that lets players walk around in one closet in return for drastically higher system reqs and that introduced gamebreaking bugs like attribute bonuses from skills not being applied to ships...

I think reducing the outrage to microtransactions is missing the point, if players were mostly content with EVE and with CCP's behaviour then they'd gladly buy virtual clothes to support their favourite game. They just chose to introduce microtransactions at a point in time where they've literally already screwed up everything else they possibly could have screwed up and did so in the most arrogant way possible.

Oooh nice making spots in CIR seem like a rare good

I can only speak for myself, but I have no problem with MT per se. I actually like the idea of supporting the developer of a game I like and getting something nonconsequential like pink paint in return.

In EVE the situation is a bit different though: A subscription is already one of the most expensive MMO subscriptions, their idea of support seems to be $20-$70 which I find ridiculous, they had previously actually announced plans to have these items made by players, when you call them on it they start rambling about $1000 designer pants, they publicly stated that their implementation of the store is so incomplete that they may have to sell spawned coloured ships until it can do trade-ins, they refuse to answer the non-vanity mt question with a simple yes or no and if they did then there's still that they had actually implemented them before in the form of paid attribute remaps, and the worst part of it is last summer they announced that EVE itself wasn't going to get any major fixes or new content while they work on Dust and WoD and code EVE has in common with them, so we know those monocles actually support their purely mt based and confirmed pay2win games Dust and WoD instead of EVE. Oh yeah and that's only the technical part. There's also those various leaked documents that show clear contempt for the player base, to which they don't even want to talk btw., they preferred to announce a one week comms silence and a meeting with a handful of players who are essentially drinking buddies of the developers on account of regular free trips to Iceland. And as if that wasn't enough it turns out they can still give interviews to newspapers, they just don't want to talk to their players.

In other words they pulled pretty much every single crap move they could come up with and now there's something for everybody to rage about. Had they implemented ship paint to work like EVE's equivalent of the plan in this dev blog, i.e. paint from the LP store and then an mt payment to apply it, I would have a hangar of pink ships now and I think it's a fair guess that most of the rage would not have happened.

5/10