Here's an old post I made on the subject,
After years of Dooming, I've come to consider them more as meat bags designed to soak damage/distract you while other -more capable- monsters target you from afar, and also to disrupt infighting.
Come think of it, they are not particularly powerful in melee: they don't do significantly more damage than an imp, on average, if you factor in how ofter their attacks miss (which also makes them worthless at infighting, which results in them just chasing other monsters around and uselessly biting the air when they stop to attack and their targets just move on).
In more detail: if a Pinky catches friendly fire, he will mostly wander aimlessly if the attacker was on a ledge, or pointlessly chase him around missing most of its ultra-delayed melee attacks, while the attacker still concentrates on the player.
They are also quite easily dispatched by SG, SSG and berserker pack/chainsaw, to the point that a sudden Pinky flood has become a staple once the player picks up the chainsaw/berserker pack, and HAS to waste two minutes dispatching them one by one.
So, do they have any other uses other than fun gimmicks/distractions/meat shields? OK, I concede that Spectres (which are essentially the same monster) can be much more dangerous, and that in Nightmare mode they suddenly become a threat, but in normal play they feel pointless: they are going to be killed anyway, are hardly gonna be a threat, and all they do is take damage from the player and other monsters, fail to fight back, and die O_o