The game and it’s weapon system is designed to be skill-based, not number based. numbers are only there to simulate a chase to strength and give a sense of reverse curve difficulty, without really changing anything.
If you want a higher challenge, than simply create its limitations for yourself like everyone else does in Skill-based games.
there is too much health in missions?
Stop using health stations and medpacks and/or quit missions when/if you go down… don’t allow yourself to be recovered, only heretics allow themselves to be captured and rescued. 
Too much ammo?
Stop looting ammo, only use what you entered the mission with. Any ammo laying around is undoubtedly tainted by chaos and should be considered heretical.
Weapons are too good?
Stop using good weapons. your 317 rating weapon isn’t an example of a bad weapon. it is a good weapon. Stats are a lie. anything above 60% stats is considered “max rolled” as you’ll get such a small increase in stats that won’t really effect the effectiveness of the weapon. If you wanna give an example of a bad weapon. Start using weapons with 30% stat to it’s useful stats, and even then you’ll probably only need 1 more hit from any weapon to kill stuff and some ranged weapons will most likely 1shot on headshots anyway.
So far I’ve only seen a handful of weapons that actually hit breakpoints above 70% stats, making that RNG chase of 370+ rated weapons completely pointless for most weapons.
Blessings/Perks too good?
Stop using them. They are clearly the biggest power level in the game as they will completely make or break certain weapons. Your Agripna isn’t using powerful blessings, but your blessing is negating the “low” rolled impact stat of your rifle, meaning that the only “badly” rolled stat of your Agrippa is actually it’s mobility stat, which won’t matter much.
Also who knows where these perks and blessings come from? the heretical machine spirits that mechanicus speaks of? they are just a fancy way of trying to make chaos sound good! heretics!
if you relay on those, than you’re selling your soul to chaos and you’ll most likely become one of the dregs and scabs in no time.
There are always things you can do to make the game more difficult. Instead of expecting the Devs to create these for you, you can help them by doing it yourself. The Mourningstar exists and there you can ask people to do missions with restrictions, or you can use external sources to find like minded people, or friends if you have those… haha that sounded harsh, didn’t mean it like that
I just mean my friends would never in a million years go on a mission with self limitations to make it more difficult, they’d prefer to always play low intense missions for instance.
Many of these restrictions could easily become Conditions for missions, or they can add crazy ones that flip things.
Like Disabled Blessings/perks, Removed Health stations, constant corruption damage throughout the entire level, No ammo spawns, or a randomized weapon at the start of the mission like a “go in blind” type of thing… procurement on site, or maybe a “randomize weapon after 10 kills” condition, Downed means death and removed from mission without reinforcements, etc
With that said, I don’t think the base game is “too easy” as you’re trying to claim.
Why? because people have varying skills and I usually switch difficulty a lot for variety and at lower difficulties(malice/heresy) I usually have more mission failed than at damnation.
Mostly this is because of players scattering, ignoring each other, hero moding or simply not being able to coup with the number of enemies, and since they are adding crafting materials and higher rewards for higher difficulties, than you have people always reaching beyond their capabilities for a bigger reward.
This is going to be a much larger amount of players than those skilled enough to farm damnation. Meaning the balance for these players will be more important than adding a new difficulty, that will need testing and tweaking and maybe only 1% of their player base will play it. Seems like a waste of their resources.
so. Help them out. Create the restrictions and game mode and invite people to try it out.
