You can't do 'fixed-camera' in full explorable 3D its impossible.
Telltale games are not 'full-explorable' 3D.
Actually the KQ8 camera isn't really fixed.
Nor is it a behind the shoulder camera. You aim it that way, but you can also aim to the front or the side of the character as well. If you aim it to the front, he walks towards the screen. If you aim it at the side he walks parallel to the screen. If you aim it behind, he walks away from the screen.
You can also zoom in and zoom out.
Further, the King's Quest series was not continued upon with MoE's gameplay mechanics in mind. MoE was the last in the KQ series for Sierra. As such, the changes they made weren't a trend or an improvement in the gameplay style. They were just woefully disparate from what the rest of the series was known for.
Not entirely true, KQ9 (2002) was going to be an action-adventure, more Zelda like (but definitely more in the vein of MOE). But it was cancelled.
The screenshots of old man Graham holding a hugeass 'master sword' are rather amusing even!
Maybe it would be a good idea to start using a seperate term for 'classic' adventure games, games such as the classic Sierra and Lucasfilm/Arts titles, and another one for just the generic pile of different games people like to classify as adventure games these days.
They were 2-d Graphic Adventures.
Although sierra used to call their early ones, 3-D Animated Adventure Games as a genre classification. Ironic really!
BTW, classic adventure games, would includ text-adventure games. Which are a different beast altogether. For a time there were purists that hated the oncoming of the graphic adventures!
More than likely QFG 1-4 or Beyond Zork would end up on that list of "classic adventure games"!
Then you have other hybrids like Fate of Atlantis or Last Crusade adventure games!
Have you ever played Inca? Adventure game/space simulator/shooter! Strange mix indeed.