After discovering reddit, one of the first things I realized was that signing up gave me a way to unsubscribe from the defaulted subs, most of which get really old, really fast; and this is when the smaller communities really shine.
As a new home owner, I routinely ask questions on /r/homeimprovement and /r/diy that get answered in a timely manner and normally by people with some level of expertise. I live in Seattle so I regularly browse /r/Seattle for the local happenings, etc. You get the point...
Getting defaulted is certainly more of a curse than a blessing for these communities. Sure, your audience skyrockets, but for anyone who spends anytime in an online community, one of the worst things that can happen is exponential growth past a certain point. I suspect the one that will quickly fall to this fate is ELI5, one of my current favorite subs. As much as I want to hold onto faith for it, I just suspect there is no way it will survive the 200 new members a minute they've seen since yesterday.
Also, they should put /r/programming in the defaults. Reddit used to be a tech community.
Despite the optimism I've seen from the new defaults' moderators, unless they moderate with the tenacity of /r/askscience I have little doubt they'll slowly descend to the same bottom of the barrel content the other defaults currently offer.
