I get that people are disappointed. I empathize with wanting to play with your pals at launch, I totally understand that. But the issue is a lot of people are coming at this from an angle that Bungie is totally moronic and making decisions that negatively impact the playerbase for no reason other than their own ineptitude. Be mad about it all you want, but the feature is there once you reach it. It's literally there and obtainable. So being outraged at it's exclusion is just as outlandish to me as me defending the design choice is to you. Ultimately, you have the very thing you're upset about missing. Just treat campaign as one big tutorial to ease you into the rest of the game features, one of which being co-op. Other games do this. They gate your access to features behind progression, that's also something many, many games do.
If playing the game on launch day is an inconvenience simply because you have to do it by yourself, how much do you actually enjoy the game? At that point it's not about the story and it's not about the gameplay for you if neither of those is enough to encourage your progression through the campaign. Join a party and talk to your friends while you all play through your own campaigns. Discuss it during your mission runs, meet up post-game and re-run your favorites in co-op. You have options that make this way less of a devastating blow to your experience than it's made out to be.