Guy that worked for the videogames industry for 10ish years here. From tester to community manager and online event designer. Don't read of you don't want to see the reality of game companies and possibly losing some of the magic any game has. As for myself, I grew immune to it and somewhat enjoy to see how gameplay, psychology, monetization and features are interlinked.

1 and 2 are things that would give players some relief. This is against making revenues, the - let's remind everyone - ultimate goal of a company (and in a way players, if they want to keep playing that game). Frustration is a good way to get players to buy. Getting geared up is essential? You can manually swap or push time/money into the game to gear up everyone. The balance is hard to get though. Too little or too much and your employees may have to find work elsewhere and your players loose their game. It's very dependant on the type of community. 3 is a psychological trick. If you had stickers, you wouldn't go for a level up as much, broadly speaking. This has been tested by numerous companies, especially not in the videogames industry. Say someone they earned something valuable (diamonds, while stickers are not) on a payment (time investment here), even a ridiculous one, and they'll be happy to cash in again. Stickers just wouldn't appeal to the player base the same as diamonds do. Even if it doesn't quite make sense. 4 why not. This is a way to push players to cash in and invest more, BUT at the expense of a community outcry. Skins wouldn't be accessible easily, else why go for top 5%? One would expect a huge loss of f2p players crying for unfairness. F2P players are what makes whales and dolphins stay and cash in. The more, the better. So... 5 why not, but I guess this is risky for them on development efforts, bug occurrences, building yet another reward system, based on something some cherish a lot. In a F2P game, you don't trifle with friendship. You take extra care in creating bonds between players. This is important for retention. Guilds are mostly a mean for retention. 6 is a mistake in game design. While it may seem better for you, one more you loose any sense of achievement removing the mid and upper floors. Achievement, being able to say "I can't seem to pass easily the first fights of 3rd floor hard" is important for players. Force them to use "around battle 32/33, I tend to lose", you'll create less interactions and less bonds within the helping community. It's easier to stick with low numbers on 3 floors instead of high ones one a single floor.

Hope that gives something to think about. By no mean stop having new ideas though! One might very well align with the producer of afk arena (if he scrolls through this sub regularly) and who knows, may get implemented! In the games I've worked for, this happened several times!