The fact that we have 5 pseudo legendary Dragons speaks for itself. Dragons not only have better Attack/SpAttack and better moves, but they have better Pokemons and most of them can take hits without any problem.True, the most reliable ghost moves are shadow ball and claw. However, either one is tough to deal with when there's nothing to resist it with. Sure, you can argue that you can switch to a normal type, but outside of the ghost immunity there's not a lot of reason to run most normals. The biggest thing to mention about ghosts is that there's not a lot of them which does help mitigate the problem somewhat. However, I can see in a few generations (at most) that we have the same problem we did with BW and the dragons. If you were to add say 10 more ghosts over the next couple gens the threat goes up immensely.
I can also promise that most pokemon won't walk away from Chandelure's Shadow Ball, 80 Base Power or no.
Although, how many sweepers do you know that don't run a boosting item? Not many out of say set up sweepers that appreciate leftovers.
They may not have a draco meteor, but they do plenty of damage without it.
The pokemon that hit like a truck with their ghost stab....
Mismagius, M-Banette, and Trick Room/Nasty Plot Cofagrigus for pure ghost types.
Gengar, Flare Boost Drifblim, Chandleure, Frosslass can hit pretty hard with its dual STAB, Golurk, Aegislash (dear lord that thing is a monster), and Jellicent can hit stupid hard if you focus on its offenses.
Mind you, some of them hit a lot harder than others, but they'll all be extremely dangerous in their respective tiers. Shoot, even traditionally 'bulky ghosts' can be threatening with the lack of resistances in the metagame.
A +2 Spiritomb is no laughing matter when you're unable to get a solid resist/immunity in on it either.
Yes, many of them need to set up, but how is that different from say D-Dance Dragonite? Except unlike before, you can't tank the +2 shadow ball with steels.
Right now, I'd have to say offensively they're by far the best type, and that's always dangerous territory to be in.
I can't disagree about the Pokemons you listed, they all hit hard, but they are frail (except for Aegislash, Cofagrigus, Spiritomb and Jellicent) Gengar and Mismagius can be 2hko and even 1hko by some unboosted neutral attacks.
Yes they hit hard, yes they have the best coverage in the meta game, but I don't think Ghosts will become a problem like Dragons used to be. They can become a problem if Gamefreak starts adding some strong legendary/pseudo legendary/high stats all around Ghosts. But so far we don't have a ghost equivalent of Garchomp, Dragonite or Hydreigon. The latest addition to the Ghost family, Hoopa looks very disappointing so far.
And, in case Gamefreak started adding stronger Ghosts, they can balance it out by adding strong half Normal types, like they tried (and failed) to do this generation. You could make a case that almost all ghosts learn Focus Blast, but Focus Blast is not an attack you can count on.
Pyroar could've been an excellent anti-Aegislash Pokemon had Gamefreak gave it a decent ability and a way to set up and raise its decent SpAtk.
And yeah, I agree Ghosts are the best offensive type this generation, but I'd say that Dark are also very close, if not as good because no one is immune to Dark and because of Sucker Punch and Knock Off (The most spammable attack in the meta-game imo).