If I was retired and didn't need to work, I'd still find some software to build and spend my time building it because that's something that I love to do. That's essentially what we were doing back then, so it was a good time.
I think there is some truth to what you're getting at with less noise and constraints and creativity.
Although - during this time, I dreamed of a future when every house and every business had their own BBS. That basically happened in the form of the www. The www and internet would have AMAZED a teenage me, it still does.
I remember that past fondly because they were exciting times for those reasons, but current times are also exciting. :)
There was lots of untapped potential back then which made things exciting. Also, the communities were smaller, like families.
But I have another explanation, which, I think, explains much of it. Being a part of the BBS network meant one had overcome a bit of a hurdle and reached a small community that actually cared about the system and the sense of the community itself. Those BBS islands had their own rules, implicitly or explicitly spelled out, they were full with lots of creativity (cf. the ASCII/RIP art), and while the occasional troll or rude idiot can be found anywhere, posting something to a BBS usually meant you got some response back. It was a smaller circle (at least, it felt that way). You could actually make friends through the BBS network. Today, when I try to post something on HN, I cannot even find it immediately after posting, let alone hope that other people find my submission. :)
The SDF.org bboard feels much in the same way.
I think we now take technology for granted and apps/sites are less special of a thing than BBSs were. Users are fickle, so much is fad-based, and we move on to the next thing without a strong feeling towards the last. Using Snapchat isn't a primary hobby or thing that you devote time to, more of a thing you do while doing some other primary thing. If that makes sense. :)
I doubt that memories of Snapchat will be as strong to a user as memories of BBSs. But who knows.