Daemons have free will, quite a bit of it actually. The beasts of the Dark Eldar do by no means stand as the core troops of their forces, and neither to the drones of the Tau or the servitors of the Imperium. In the latter's case, most forms of AI will actually make the techpriests claw your eyes out. As such, mindless units only are a small minority amongst these groups. In the Necrons, by comparison, the bread-and-butter warriors are little more than automatons, and the autonomy of Immortals is questionable. Compared to, say, the SM faction, this would mean that all Tactical Marines would be remote-controlled robots. Those Necrons that do have free will are a minority of elite/hero classes - Lords and Phaerons, Lychguards, probably Eliminators, and Triarch Praetorians. Maybe Flayed Ones, but they're all kinds of messed up. So, in order to make Necrons playable, you'd need to have all players play elite classes only, kinda like making all CSM players Aspiring Champions.
you start with immortals as a base class, all other below it will look wrong when player controlled since theyll be doing things they probably wouldnt, and theres still enough classes/units to make a feasible play list, and if we're being honest any space marine is an elite when compared to an IG or SoB
Immortals as a base class might be feasible. Space Marine being elite compared to IG is true, but then again Lychguards and Praetorians are elite when compared to regular tactical marines.
if we can live with the nerfed ranges for weapons EC will have then a little bending of the stats isnt that hard to swallow, obviously BE think they can pull it off since they put necrons and tau on the list of possible 5th factions
Daemonic Creatures, which are a substantial part of Chaos Daemon forces, are not sentient. And Dark Eldar beasts are an important and very recognisable part of Dark Eldar armies. And I can perfectly well field a Necron army on TT without a single non-sentient Necron. Immortals, which are fully sentient, count as a basic troop choice.
Daemonic Creatures and Dark Eldar Beasts may form a part of their respective armies but are not their bread-and-butter choices as Necron Warriors would be for the Necrons. Again, the questions whether Immortals are sentient or not (in the sense of autonomous) is complicated - they can rely on millenia of battle experience, but can not gain any new one, for instance.
The codex is quite clear on this. They can speak, deliver battle reports, issue orders, etc. Just because they are limited conversationalists and can't learn new tactics doesn't mean they are not individuals. Compared to the average Ork Boy they seem pretty smart.
