( tl;dr read the last line for the question. I've also tried to avoid some spoilers but go full at it in the posts. )
In Vanilla, there was a certain degree of mystery about the Old Gods. We saw glimpses of what they were capable of doing across the zones. Quests and NPCs would have us have breadcrumbs towards who and what they exactly were. World of Warcraft at this stage was in a fresh time for forging its lore. It had many stories and things to follow from WC3, but WoW began to take its own course for story-telling.
There was an eerie feeling with the Old God story-line. The Lovecraft-inspired baddies made things a lot more complex. Sanity and influence over the mind is a very deep topic, a little heavier than what the usual 'go slay ten boars and save a city' kinda deal. How they were so weaved into Azeroth and sealed there, unable to fully be killed without causing damage to the very planet.
We fought C'thun. We heard his creepy whispers to players.
BC took us into a different route. Not entirely focusing on the Old God story-line. But soon enough. WoTLK came.
Yogg-Saron's plot was wider spread into the questing zones. Ranging from saronite's origin into the open corruption we saw in Grizzly Hills, we as the players were drawn into something deep and terrible. Ulduar reflected this perfectly. Where as AQ rightfully felt like a temple of power, of worship for C'thun the players instead were brought into a prison-like scenario. The deeper we went into Ulduar the more we saw how the Titans tried to contain Yogg-Saron.
Cata hits. The black dragon flight and Deathwing himself are all victims of the Old Gods. We battle against cultists and travel to the Elemental lands of the Old God's lieutenants. Dragonblight falls into corruption and we hints of another named Old God here in Dragon Soul. It's almost too much to take in at once. The zone revamps in certain old-world areas also reflect this.
Then we here with that named Old God and further corruption. But something is lacking. Somewhere and somehow the who mystery, the whole terror of these things got a bit too stale. We're being given another set of breadcrumbs for suggesting the black forest. Yet another thing lurking below. But it's gotten tiring. Has the Old God corruption or story-line in general lost its appealing touch? Granted, I'm happy we are being told some origins. It just feels like the story has been done too many times and too open about it as well.
Are you pleased with the Old Gods and the corruption stories we have now? Has it gotten better or worse would you say?