I think the complaints stem from the idea that staff-hosted events are a competitive aspect of the game. The truth is, they never were. The fact that you have over 60+ event hats or have completed the collection already proves that you are good at staff-hosted events, so there is no need for further rewards. If you want to show how good you are at the "gameplay" such as Bush race or Cliff climber, you can do that by winning carnival events multiple times since they are shown in your statistics. If I have to say one thing, the carnival events should include games that aren't included at the moment such as Sumo, Math race, Scribbles and etc that require "skills" and not "luck" - Chance, for example. The amount of wins could be added to leaderboards to encourage competition among players.
The whole situation that there's people complaining about not being able to enter most of the warpers because they already have the hat is ironic, since more than half of the playerbase have less than 10 event hats. I even know a player who has played since 2009 and only has a single event hat - which was from an event queue. What the eventers need to know is some people have never entered a warper or even know what certain event looks like, and some are tired of seeing the same winners in event messages every time. You might blame them for not trying hard enough to find warpers but the reason they gave up long ago and don't care is because warpers would fill up so quickly and winners would always be the same. This kind of change was something expected and maybe it's just about time to let other people get to know the fun. From time to time, new event hats would be added so for people who already have majority of the hats, they don't need to worry about not being able to participate.
I'm sorry to hear that there are bugs not letting people enter when they don't have the hat and this is definitely something they should work on. I heard people say it didn't let them enter when they didn't have the "recolor" but even before this new system, giving out recolors of event hats was an optional thing and you technically have the same hat, so in this case, it wouldn't be an issue. I used to be in an event guild myself, and I know eventers enjoy finding warpers and participate but I just wanted to be fair.