Groupees hate comes from a few places, and several times it does seem reasonable.

Slow payment and nonpayment of devs was a big one. Then you had the time that their servers exploded- while they did make an effort to restore things that were there, some people lost access to content because they trusted Groupees would maintain it. More recently, you had the somewhat less than above board move they made with Johnny Antimatter coins.

Before the BMA Preorder was created, Johnny Antimatter coins were "worth" $15. After the BMA Preorder ended, Johnny Antimatter coins were "worth" $7.50. The could have very easily created another fluctuating value coin, pegged to whatever level they wanted... but they chose one that they tanked the value on by reintroduction of it.

All of this taken together with the questionable level content in many of the the blind preorder products, you have lots of people with very little faith and trust in Groupees.

While some of it IS people just being ridiculous because they want $100 of value for $1, there's plenty of things Groupees has done to earn a little bit of the ire pointed at them.