When Obama was first in office - when Dems held Congress - people were pretty cool with criticisms of him. His faults couldn't be blamed on Republicans - though a few bad Democrats - and people were open to that. After 2011, people just didn't want to hear it. The thing is, Obama did a lot of bad stuff. He also did some good stuff! Obviously I think Obama was better than Trump, Bush, Bill Clinton... by the standards of the presidency, Obama was good.
But he was also bad. The housing/financial crisis was bad and he fucked up on that one and we are still paying the price.