Gregory's Server@kepano I think there is also an issue of it being an online servise. You can make an offline product for free out of love, and then, when you lose interest or run out of resources you can just abandon it, maybe open-source it, and it still going to work. But with online thing you need to pay for the servers and provide constant support, which is hard to do endlessly on pure enthusiasm...
That said, I really hoped they will add some way of monetisation, instead of shutting the app. They said they were planning to do this when people asked about their business model. But, I guess, they decided it wasn't worth it.