I think the problem with Dick though is that before the reboot he was arguably DC's most featured character. It was probably the most exposure the character has gotten in a long time, maybe ever. So to go from all that to just appearing in Nightwing in the New 52 was a very steep fall. Which we all generally expected as nothing can replace being Batman, but what made the transition to the New 52 so bad/painful, as compared to a Steph or a Cass situation, was the slow and spread out process of seeing important pieces of his character and history being picked from him and given to other characters or just erased while he is left with less and less. As the reboot continues to unfold we are still learning just how much he has lost, from history, friends, experiences, stories and general standing in the DCU. Finally with Grayson it seems they have stopped some the bleeding and are trying to build something up for the character. It was a much needed step.
Steph and Cass fans have every right to be just as upset, but their situation remained pretty consistent from the start. They were taken off the table completely and are being rebooted from the beginning it seems. They didn't really have to see their characters continue to fall further and further as more time went on (though I guess Cass fans experienced that well before the reboot happened after she quit being Batgirl), and even with Tim, who has no question been written far worse than Dick in the reboot, was at least given something like founding and leading the Titans to make up for some of the things he lost. Dick wasn't really given anything to make up for the things they took from him. So he was just Nightwing again, but a shell of what he was before. So it made the situation frustrating as it left the character with very little to work with.