Join Date: May 2009
Location: Beyond the Glass Mountains
Considering what the Iron Warriors say in Storm of Iron, the pre-heresy Marines were not "better" strictly in terms of performance, but that they were more like great warriors/knights than the paladins they are today.
They used to fight for the unification and protection of Mankind and its interests, but these days they're fanatical followers of the Emperor, although not every Chapter is equally zealous (compare the Space Wolves and the Black Templar, for instance). There is a huge difference between following an ideal and following a person, be it mortal or divine. You could say its like the wolves vs dogs situation, where the wolves are free and the dogs serve humans. But while the wolves work on a "might makes right" basis, the dogs do whatever their human masters tell them. So its essentially individualism vs lawful society.
Because of this, the CSM view the SM as fellow marines who abandoned their free thinking, which results in predictable behavioural patterns and thus predictable goals and strategies/tactics. So in a sense the "young" SM aren't "worse" in terms of performance, but their new way of thinking narrows their vision. The extent of this of course depends on the given Chapter and then on the given individual, but overall it works. And for safety's sake, I used the CSM perspective because they are the best at telling the difference between old and new SM.
The fool, the coward, and the ignorant proclaim that the warp is a realm of unknowable peril and indescribable terror, that it is the hell of countless ancient myths and legends. This is a lie, told by those whose authority is based on lies, to keep the masses terrified of the unknown. The warp is limitless power and its secrets are infinite; it is knowledge and strength, life and death, and the untapped potential to make and remake worlds. It takes only the discipline and the will to shape it; those who lack that clarity of purpose are liable to be shaped by it instead.
- Ahzek Ahriman of the Thousand Sons