I know nothing about WHFRPG, so I will refrain from commenting on that, but I think fans are far less opposed to mechanical innovation than what you seem to imply. It is just that different groups of fans would like the game to change in different directions.
For example, I am not at all fond of 4E and have not switched to it from 3.5E D&D. However, I would be able to stomach changes to the game of the magnitude that 4E wrought, had they been in a direction I would find appealing. Hence, I might have welcomed huge changes if instead of homogenization of classes, they had been made more heterogenous in terms of their abilities, or if a greater emphasis had been placed on out of combat abilities and so on and so on.
There are many directions changes to a game can take. For me, it is not really the scale of the changes that matters (at least not up to a point), but rather where the vector of the changes points towards.
For example, I am not at all fond of 4E and have not switched to it from 3.5E D&D. However, I would be able to stomach changes to the game of the magnitude that 4E wrought, had they been in a direction I would find appealing. Hence, I might have welcomed huge changes if instead of homogenization of classes, they had been made more heterogenous in terms of their abilities, or if a greater emphasis had been placed on out of combat abilities and so on and so on.
There are many directions changes to a game can take. For me, it is not really the scale of the changes that matters (at least not up to a point), but rather where the vector of the changes points towards.