i’m playing on auric damnation, and it’s become a regular thing where i’ll have a health stim, i’ll ping an extra one on the map, and my teammates will just run by it and not pick it up a lot of the times they have multiple wounds and corruption, too. i know there can’t be that many people avoiding them just to make the mission more challenging lol
is there something about them i’m missing because i’m having trouble understanding why people would be avoiding them so often now 
Bad awareness.
People also often do not pick up pinged medipacks, and leave charges on medicae stations.
Although those have the generic + icons and although pinging medpacks and med stations comes with a callout by your character, which mentions the specific word “medipack“ or “medicae“, people are still blind and deaf and do not notice them.
Medi stims do not have the intuitive + icon and if i am not mistaken, tagging a stim does not come with callouts that specify the effect of that stim, so people will be even less likely to notice them.
Your average player is blind, I say it on the Voice Chat twice, and if you still don’t take it another thing I take note of as I decide whether I hate playing with them or not.
Suicidal zealots saying “but mUh DeePS!?”
it’s not even just zealots, though lol people with empty inventories of all classes are just walking by pinged health pick-ups on a regular basis now.
Fair enough, they’re just the more frequent offenders in my experience.
People constantly take anecdotal experiences like this and want to extend their experience to a greater pattern. However, these experiences are usually not representative of overall trends, and are often colored by human biases. For example, negativity bias leads people to remember those times that people don’t pick stims up more often than the times that people do pick stims up.
Having a health stim is THE play for a martyrdom zealot precisely because you can remove corruption while maintaining low health.
Hot take, but the health stim is the only one I care about. The others are honestly not that noticeable, are short duration, and sometimes just cover my screen with an annoying effect.
With my crit tac axe zealot the speed one is nice… but health is generally better overall.
As @Flawless said, bad awareness is probably the usual reason. Same reason they aggro DH’s despite multiple tags and someone mentioning it in chat, don’t pick up nades or ammo or deployables, don’t use medstations, don’t help netted or doggoed teammates etc.
On a personal note I almost always prioritize Concentration Stimms myself, especially since I main psykers and usually go with Vent (sometimes bubble). That Stimm adds such an ungodly amount of DPS and control that for the next 20 seconds nothing the game throws at me will be anywhere near enough, making it far more valuable than healing 1 block off of a random teammate. Obviously I don’t leave resources unused however, if nobody picks the Med Stimm up then I’ll just use it on someone anyway.
…Unless I have to go running after them in which case it’s their problem. After Oct 3:rd and all the new players, I honestly stopped caring. I’ll tag resources ofc, with priority stuff like deployables or medstations (or big ammo bag if ppl need it) I’ll even put a “look here / go here!” tag on it so they can see it from a distance. But I won’t waste a single extra second on tagging it multiple times or typing in chat. If they don’t pay attention its their loss. And if it’s something I have use for like an extra med/ammo kit, if they don’t react I’ll just slap it down then and there and move on. 
There are stims in the game? What are they look like? I don’t remember seeing those since the release of the game. The only healing I’m aware of are the stations and the crates.
They are relatively new and only came with a recent update.
This, HP stim is like the heal draught but better (hand off + use on allies). The others are way situational. Combat stim is about the only other one I’ll hold onto, because it lets you kill harder when faced with a bunch of armor. Very rarely used still.
Oh, that explain why I didn’t notice them. I feel the game is really lacking of crucial explanations. Same thing for weapon stats. I still have no idea what finesse is.
People are blind sah, I stab them with the pointy end and go pick it up. Unless its green, I wuz told…but I dont know whats a color…
Go to the psykhanium.
They are on a new table there.
They were added in one of the recent big updates.
Finesse is headshot and crit.
Most people don’t even pick up P L A S T E E L, then get mad that you run off to collect it.
Thanks for the info but what is the psykhanium?
Meatgrinder/test room