Online games NEED global chats.
Indeed, they're filled with garbage most of the time, but that's not the reason they're needed. That garbage breathes life into the game, by making you aware that people are there, and contrary to what people think, they aren't ENTIRELY useless. There are still meaningful interactions there, people are exchanging information, asking questions, asking for help, making arrangements, deciding to meet each other, and they at the very least pop in to say "hi!". It's a key element to the creation of a cohesive community, and actually a prime aspect of fighting against griefing: if people care for each other, they won't be so tempted to annoy each other, but they will be more temped to help others.
Because online games NEED global chats, if there isn't one, players will create one. I'm myself already seeing how well I can integrate a variety of chat overlays to the game, and if the game doesn't have one, then I'll pick a nice IRC channel, spread it among the community, and we'll make it our home.
What's the difference? Well, if the global chat is a third party alternative, it splits the community in two: those that are on the global chat, and those that aren't; worse, there could be several alternatives. So the game better have one, and those that don't like it will just hide it.
The biggest problem I see with this is that we're talking about a space sim. There's hardly any place that's safe, where you can just sit back and relax, and leave your stick to grab your keyboard. That's a problem we could be working on. I'm considering text-to-speech software for that, but I'm not sure it'll be good enough.