nothingspringstomind said:
You... really don't get how technology works in 40K. The height of human technological advancement occurred thousands of years prior to the setting's "current day", and is now referred to as "The Dark Age of Technology". The keepers of technology venerate machines as facets of the Omnissiah, and believe that rituals to appease the "machine spirits" are required for them to operate - in short, scientists have largely been replaced by a religious mystery cult that for the most part considers innovation to be heretical; the technological rate of advancement since the 31st Millennium has slowed to a crawl, and most of that prior to the Horus Heresy was simply recovering schematics and designs that humanity had already created in its distant past.
The Imperium as a whole is collectively losing knowledge, and the production of new technology is as much ritual as it is manufacturing in many cases; superstition reigns and reverse engineering is an affront to the sanctity of the machine, so you have examples where the Mechanicus knows perfectly well how to produce grav-plates for their warships but cannot then replicate the technology on a smaller scale to produce a grav-bike, even though they
have vehicles that work on basically the same principle now.
Mass Effect is your standard Science Fiction vision of a bright shiny optimistic future, 40K is what happened after mankind already had one of those and it all went to hell in a hand basket - you are talking about a society that produces maxims like "An open mind is like a fortress with its gates unbarred and unguarded". The rare few brilliant technical minds or innovators are exceptions to the hidebound stagnation that sees extremely advanced technology operated alongside stuff less advanced than what we commonly use now; loading the cannons on an Imperial ship of the line is done
by hand, by entire teams of men.
But with that said the Imperium uses a whole bunch of energy weapons, lasguns are standard issue equipment to the Imperial Guard.