I also think their egos cost them big time in S7. They thought the rebooted show could go on for several more seasons. If they had been realistic about it, they would have made S7 more of a self-contained, short-lived curse with the goal of reuniting Henry, Regina, Hook and Rumple with their loved ones left behind in Storybrook. Instead they brought the wish realm back, added 100 new characters, made everything super convoluted, and lost chance for any real emotional attachments. For me, once I saw 702 and knew that the real Hook was happy back in Storybrook with Emma, I had no desire to watch the rest of the season.
If it had been the real Hook, who had actual connections to Henry & Rumple, separated from Emma and trying to get back to her (and maybe looking for his and Emma's daughter), that would have kept me watching. But they knew they couldn't drag that out for multiple seasons, so they had to bait and switch with a new version of Hook and a daughter that not only wasn't Emma's, but was the product of a rape by deception. So even though they kept Colin (who played my favorite character in S2-6), they removed anything that would have made me want to watch.