That is what I think 40k is getting away from. No more can a simple soldier with the determination and the right tools defeat a treacherous foe. We will never see a lone space marine armed with a holy sword fight off a greater daemon. He would have to be blessed by the emperor himself, wearing terminator armor and at the moment of the battle be gifted with extra pixy dust, and then he can defeat him.
One runs the risk of stretching the willing suspension of disbelief otherwise.
My counterargument is that 40k has seldom, if ever, been about the "little man", as it were. Certainly there is much individual bravery to be found from ordinary men and women, but in the grand galactic scheme of things, no ordinary individual in 40k has ever had strength or influence enough to change his fate - usually death in some form or another - or otherwise shape events in the galaxy, or even his own sector. That's why so much attention is paid to "extraordinary" individuals - Space Marines, Inquisitors, high-ranking and inveterate officers, etc. - since they have been gifted with enormous strength and influence enough to shape events and lives around them.
At first glance, the focus on such powerful and nigh-invincible individuals runs counter to the theme of the lack of importance of the individual, but it's also important to remember that most of these individuals were chosen
, rather than chose
, to possess such strength and influence. Space Marine Chapters choose their initiates and aspirants from children found to be especially adept in combat, and Inquisitors choose acolytes according to whatever need they have at the time, and choose Interrogators and their successors from among their most skilled and trusted acolytes. None of them got an option to say "no", or at least to say "no" and remain alive. It is ironic that, despite possessing such magnificent influence, such powerful individuals were never masters of their fate to begin with.
Taking the focus off of "ordinary" men and women and instead choosing to focus on these super-powerful individuals actually reinforces two key themes commonplace in 40k: the insignificance of the individual and individual choice in comparison to the survival of the group as a whole and the powerlessness of all men and women to control their own fates. It's this deterministic and nihilistic philosophy that guides much of 40k lore.
Hopefully I wasn't too off the mark there.