The reason for a tool to exist is to be used, even if it's just by a singular person, other projects that aren't tools do definitely fit into the criteria "just for the joy of it" but a tool, by definition, has at least one usage, and building a tool gives someone joy from the tool being useful.

The sadness doesn't need to be focused anywhere, you can feel sad for more than one thing at a time. People can be sad that a tool they think is great, have relied on, and has been important for their use case is going away while also be sad that such a great tool doesn't get enough support from companies. Both can be true, no need to control what people can or should feel.