I am not sure how old you are and if you actually played 2nd edition but the reason they changed from a skirmish level game, (which it wasn't actually, it was company level, non Space Marine armies, especially Orks and Imperial Guard would typically have 80-100 odd models) to bigger forces was because thats what people wanted and that's how people were playing it.
People weren't complaining that the game was too small and they wanted to use more models, they were using the models anyway and complaining the game took too long to play. They wanted to use their collections, to make massive, impressive armies and use them on the tabletop and they wanted to game to support that aim.
GW didn't betray the roots of 40k, they did exactly what the players wanted.