Rubbish technology like personal laser weapons, anti-gravity technology, and interstellar travel, you mean?
Yes, rubbish technology like interstellar travel using a bible and sacred oils, lasers that can barely penetrate heavy armour, and anti gravity technology that is deemed heretical by the holy order of Terra.
Excuse me?
Regarding the lasgun, what you're failing to remember is that it's an assault rifle, a basic infantry weapon. It's not designed to blow holes in tanks, that's what the lascannon's for. It's designed to a be a rugged, reliable piece of kit, easy to use and manufacture. It's pretty much perfect, in fact, for what it's designed for.
If anti-grav technology is heretical, why are aircars
common on many Imperial worlds, not to mention Astartes Landspeeders?
I will give you prayers to the Machine Spirit, but it's hardly a massive inconvenience in any case.
Besides, name any of those that we do better now.