We could share a lot about the decision to include Campfires/Pings in Basecamp. But briefly, to answer your Question 1:
Basecamp is most effective when it’s the “one place” for a group. The more you make it the central hub for a project or team, the better it works. We found that we were using Basecamp 2 (the previous version) for all of our projects very effectively, but we also had companion rooms in our separate Campfire app all the time. And we used an internal Jabber service for instant messaging. We concluded that real-time messaging is table stakes for getting a team to run smoothly.
But there’s a difference between seeing something as a requirement or table-stakes vs. making it the core of the product. Synchronized, real-time discussions are peripheral in Basecamp. They fill the cracks between the asynchronous features, which are at the center of the bundle. The discussion threads on Messages, To-Dos, Automatic Check-Ins etc are what allow you to manage lots of stuff at once, reduce your stress and give you more free time for quality work when used properly.
I’m not sure what you’re asking in your Question 2. Real-time feedback within the chat tool is a no-brainer. You’re already a real-time context. Just because the app is positioned more toward async overall doesn’t mean that specific feature in a specific context can’t have a real-time element.
Hope that clarifies. There’s a lot more to this than making a rule and applying it as a blanket policy to everything in the app.