If you had to pick 3 reasons to hate Early Access...

...What would they be?

Mine would be

1. People complaining about a game that's in alpha/beta, like it's a finished product.

2. Developers abusing the early access title (looks harshly at Nether) and using it to get da moneys out of the customers and never finishing their game.

3. I guess on-top of that you could add dumb-ass developers who don't listen to their customers for suggestions and ideas for their game.

Also cause I love all of you, I decided to add a Key Drop

Edit: I decided to add Chambers comment up here because I thought it was pretty awesome and legit.

1) Free work. Getting buyers to pay to do playtesting work, which is work they should be getting paid for, not work that they should be paying to do. Dealing with an Alpha is work.
2) Investment without return. Turning buyers into investors by getting money from buyers for development, and thus those buyers assume the risk of a potentially failed development. But unlike a normal investor, there is no chance of a return on that investment.
3) Lack of incentive. Once the devs have payments, there is less incentive for them to finish the game. Because, they got your money now, and they won't get any from you when they do finish, so the only incentive to finish is pride in their work.