Well some necromancy summons have own stuff,ghouls can paralyze,hamunculi have sleep touch,statues have immunes.etc.
Corpses gives only HP and speed(?) afaik.And Necros stay one of the best classes.Too OP for this numerous variants of necromancy.
ToEF can be solo with cold spells.

Corpses from monsters with really powerfull special abilities are rare enough to not make necromancy OP
also I wrote that inheriting special abilities maybe should not be 100% guaranteed...

Maybe only undeads with only useless special abilities (that have no effect on monsters)

for example:
shadow - strength draining
corpse-fiend - sickening attack
wight - toughness draining attack
wraith - toughness draining attack
mummy -sickening melee attack
ghost -aging attack
spectre - Strength and toughness draining melee attack
vampire- Strength and toughness draining melee attack
shadow lord - strength draining melee attack

should inherit one random special ability from corpse in replacement so monsters with
stat-draining, aging and other usless ability should have chance to inherit special ability from corpse -- that would be fair enough to compensate their incompetency when fighting on necromancer side :)

For me inheriting 100% of speed from quickling corpses is making necromancy OP but not my proposition.

My proposition could change necromancer playstyle so
he will hunt for certain types of humanoid corpses dependant on in-game situation.

Why necromancers should be forced to play wizard style in ToEF ?

Eh, I kind of would prefer this if other aspects of Necromancers were nerfed instead. As is, they are largely wizards with Find Weakness and Food Preservation, in return for fairly suboptimal class abilities. I agree that Necromancy is more of a bother than it is a boon often, and this might help rectify that.

The risky abilities are penetrating melee attack and regeneration. Bards already have access to Claw/GreaterClaw/Killer bugs, which admittedly can solo the game on their own. This *would* make Moloch undead fairly absurd. Still, might merit testing.

-- u cannot animate moloch corpse I've tried that several times with 100 necromancy
-- bards cannot tame bugs anymore

HP regeneration is already inheritable from corpse the point is that most of the undeads have many abilities that are completly useless when fighting other monsters (aging, sickness, stat draining etc.)

Alternatively, make these abilities not useless against monsters. Why not have their abilities be based on a more intricate system, like with the PC? :)

How do you implement St/To/Age draining when monsters dont have age and some attributes that PC have ? But I think sickness would be easiest to implement - just divide monster HP and damage by 2 instead of just message "The <foo> looks somewhat green"...

That would make mummy / corpse fiend somewhat usefull in early/mid game.

My somewhat joking suggestion implied revamping the system, treating monsters as more complex entities not unlike the player. Obviously, doing something like that is neither feasible in the short term nor necessarily desirable.

EDIT: Never mind, seems they are actually going with (among other things) making full-on player-equivalent entities out of everything in the future, according to the currently airing twitch stream of the Roguelike Celebration.

This. It doesn't have the exact effect as on player:
strength draining - reduce monster damage
sickening attack - somewhat like poison
toughness draining attack - reduce max HP
aging attack - chance to instant kill living creature