Hogan's heel turn was needed and it came after 12 years of being the ultimate good guy so it was more of a shock than anything else, which is why it worked so well. Of course, he was a heel early in his career, but most people watching by then only remembered the hero Hogan. Same reason Cena could go heel in a year and there'd be a number of teenage fans like
He was actually getting booed as a face at that point, so it wasn't like he was universally loved before he turned. Undertaker's last heel run lasted about 6 months and ended because people were cheering him anyway.
Jericho bounces back and forth- that's why he can do it. People are used to seeing him in both roles. Some even like him more as a heel.
People like Rock, Austin, Taker have damn near unconditional love... they could be turned heel, but who'd boo 'em, and who would they cheer for in going against them? Take for example, Undertaker. I remember when Jeff Hardy was clearly the most popular star in WWE ('08-'09), and one night he hit Taker with a chair and the crowd booed the shyt out of him for just that moment. That's how much people like the Undertaker. And especially since he now only wrestles once a year- ain't a chance in hell Taker's gonna have his one special match at Mania and get booed during it.