Global channels are not meant to be a replacement for the party seek feature as that's something that is, hands down, needed. But, I feel global channels can fill in the gaps when a party seek feature falls short.
Yea I know, that response was specific to the person I quoted I know you're all not that shallow.

Suppose, if you will, Joe Blow just pick up some leves in Ul'dah and while he can solo them all, Joe would prefer to get together a small party. Now, Joe could try the party seek feature and hope the people looking for a party wouldn't mind doing some leves for a bit or he could shout right next to the crystal and hope someone is actually there and willing to help. Or, perhaps Joe could send a message to the leve global chat channel that he's about to do leves at X, Y and Z and wants to see if anyone is interested in joining him.
And when you put it this way it gives it some merit, its a good example I'll give you that. I didn't say the system was completely useless but I was saying from my experience I dislike it because its a spam fest most of the time and a lot of trolling, its really no better than what goes on on these forums...hey maybe FFXIV will change its outlook if its ever implemented.