Well...
My biggest complaint was that the top prize, the free Pool Party Mundo skin, was impossible to attain through free play alone.
It is my belief that, in order to reach that top goal, either more players needed to buy and spend RP in the proscribed manner or players that routinely buy and sell RP needed to spend more of it during the time period. In other words, the top goal was not possible through just playing five-man pre-made games, which more than often required complete strangers of varying skill and rank levels to create.
This is the purest example of a cynical "win-win" scenario I can think of. Either Riot recoups their losses from giving away a free skin and champion (a maximum of 1560 RP, or around $15.25) or they get to keep the money spent on RP if the project fails. Frankly, this goes against many public statements made by the company, yourself included, that Riot didn't want players to feel compelled to spend money on their game (such as the long abandoned Lifetime RP Rewards project).
Of course, someone is going to chime in and say " but we got so much out of it." Let's take a serious look at how much we actually got, shall we?
Tier 1: Team Up Week IP Increase Great, an opportunity to get more IP that I can't use for anything.
Tier 2: Tons of Discounts: Great, more ways for Riot to get money out of me.
Tier 3: Free Icon and Random Champion, Skin or RP (if I participate in the Facebook Friends program) Great, I get a random thing if I help a pet side project of Riot's inflate their numbers. Hell, some Rioters even said that you could use a fake FB account to join, so those numbers are definitely skewed!
Tier 4: Pool Party Minions Great, a cute visual upgrade to minions for one patch's worth of time. It would have been nicer if it was an option you could turn on within your client for your own game's visuals.
Tier 5: Party IP Weekend See response to Tier 1.
To me, this really doesn't sound like we got a lot out of our efforts.
As far as Riot "recognizing a lot of problems around it" goes, I think the fact that the event's team didn't bother doing an AMA after the players failed to reach the top goal (and barely reached level 4 at that) speaks volumes on how that team and the company regards this little experiment. Everyone I've talked to at Riot in a quest for answers about this has been silent, save for one person who said "we mistuned the numbers" and wouldn't elaborate when pressed.
Bottom line, I do like Riot for most of the things they've done and try to do. I've also been been critical when things aren't going as I believe they should be (Yorick), but The Pool Party / Team Up Week simply felt like it was impossible to accomplish without doing things that go against Riot's long standing policies. I don't think it's greedy to ask for a realistic shot at reaching a group goal.
Honestly I think we f*cked up a bit on a couple of pieces of Pool Party. Without going into too much detail, 2 of the problems I saw in hindsight were:
1) We were not clear about how the goals were meant to be earned. Pool Party Mundo wasn't supposed to be obtainable without an increase in spending. This was intended. But we were not upfront enough about it and set expectations wildly off from where we wanted them to be.
2) We rewarded gifting because in general, players have reported great satisfaction from sending gifts. But by providing incentives to gift without guarantee of the payoff, we set players up to feel bad about the purchases they made. This is something we absolutely never intended.
We would definitely make changes to those two issues and more if/when we run a community rewards event again. Ultimately though, players in the aggregate did appreciate pool party based on our surveys. Sure, the vocal Reddit wasn't pleased, but Reddit is actually only a portion of our player base. One thing to keep in mind is that while Tiers 1-5 didn't matter to you, it did matter a lot to a lot of players.
And I really appreciate your well thought out response.