Falling In Love With Ideas
There are some wonderful ideas in technology that regularly inspire projects, but their primary idea hasn't yet become the default mode of computer usage.
They've motivated some excellent hobby projects, but tend to get stuck there.
For example, the concept of a memex was introduced in the 1945 essay As We May Think.
Project Xanadu was/is an extremely ambitious project that described much richer hyperlinks than today's web.
Are there others?
Other examples include Lisp Machines, peer-to-peer/federated protocols, augmented intelligence and mesh nets.
Does that make these ideas bad?
The important thing is recognising this risk, and planning ahead.