Literally broken too, at 0 Durability.
Damnit, could have told me earlier!
Those messages were actually from the developers, not other players. I don't like that. I was with EpicNameBro. Oolicile was referred to by Dusk as a land of light based sorceries. If you look at the sorceries she sell, most of them are light based. My first reaction when I heard we were was that I should bring a light source such as the Cast Light Spell, the Sunlight Maggot, or the Skull Lantern. That the developer just left messages saying "Use light to get this secret" ruined any chance at discovering secrets for myself.
I don't mean those developer hints, I mean others spread throughout the main game that were legitimately left by other players. I had already saved Dusk, so I ran to her and that cave thinking I could get straight to the new content, only to find messages strewn about from others...
"Dark ahead"... "Be wary of dark"... "Hidden path ahead"... "Here!"
I was stumped, until one finally appeared that read "Try crystal". I'd just killed all those crystal golems and already freed Dusk, so where else can I find-- aha!
That's the beauty of the messaging system, right there. It's PLENTY to let you find practically all the game's secrets. It just takes more time and patience than checking on a Wiki. I can understand why people would turn to a guide after getting frustrated, but it's not necessarily the game's fault you caved (pardon the pun).
By the way, only one of Dusk's sorceries is "light based", so I'm not sure how you reached that conclusion. What she tells you about the magic of her land is:
Oolacile sorceries are, what doth one say? They are somewhat… of an approximation.
Thine sorceries are more straight forward, negating all but thy self.
Which is still a bit obscure for you to be running around the whole of the new content flashing light sources everywhere that looks suspicious...
However, I do agree that "Let there be light" was too simple. They need some good old classic video game notation, like burnt out torches on the walls, or a natural ray of light flickering on another wall, revealing the possibilities of hidden paths.
I imagine even if there was no message in that particular spot, someone would have eventually found it and put a message saying "Try light", and the joy would have spread. It's just that this was a particularly important item that perhaps the developers 'recommended' for the following area, and didn't want too many players to miss it. A quick scan of the item description lets you know it's pretty worthwhile.
I dunno... maybe we'll see more of those 'cryptic' dev messages in Dark Souls II in an attempt to make it more accessible. You should really leave that up to the awesome community, though.