It's not free. While there is a lot of theoretical opportunity for bonding, it's still just a temporary commercial enterprise.
For anyone who has lived here, it's a known fact that Estonians won't exactly engage with strangers in a warm way, if at all. Smiling at strangers is considered poor social form here and it doesn't matter if you're a foreigner or native.
It does increase social cohesion amongst neighbors at least for a week or two. Kodukohvikud are a unique experience but it's not really "inviting strangers in my backyard" in the way a free community oriented and socially engaging event would be. Naturally, the article will only show the very few who have a story to tell while ignoring the fact that 90% of them don't have one to tell.
You get your keefir, you get your viineripirukas, pay for it, eat isolated with your family on a table and that's all most of the time.
It's akin to someone who makes pizzas to sell in the terrace to passersby. Really cool, quite nice but again, weird framing because you wouldn't say that about "Jean Paul who sells pizza from his balcony", so to speak.
I still love it, though!