Sorry to say but have you seen the facebook announcement? People screaming for the achievement reduction are still busy, because is still too hard! Hell i had to explain to some of them how to actually play in the arena and turn off auto fight.
Most complaints did not come from people where it was too hard, but from people who lacked the knowledge to do it. And in the end for what? Nothing, because they still cannot complete it due to having to weak heroes. People will always cry about something, and it is a shame the devs give in to it.
Hi there,
The dev team went through all the current player data and community feedback before arriving at this extension.
We realized that players who spent much time on it previously will feel aggrieved, so please accept our apologies for this final hour decision.
The team will strive our best and communicate with everyone earlier in the future events.
it's okay! we know you and the devs are doing your best and with good intentions!

mistakes happens but you guys is still doing great! i really can't wait to see how big this game will grow.