I could put on my patio11 hat and say "Just charge for it"
One extra benefit is 'please sign up for email updates' which while in almost all cases not mandatory, comes with text like "stay up to date" or "receive insights".
I usually do sign-up, and this keeps the person providing these updates with another potential customer for other stuff, and me with usually useful (as I've self-selected as being interested) and interesting updates.
Win-win.
You could tell them about updates, new projects or terrible bugs
Hmmm, making a more open Humble Bundle type shop could be a neat idea, and I see that openbundles.com is currently available.
A free open bundle library would make this a lot easier, but if someone writes one, for the love of god, dogfood it! We can't have you starving in the streets while trying to make other altruistic developers money. ;)