I mean, on one's own time, this seems like rather a good thing to do.
But to say "Yeah, instead of something that works now 0 days work let's spend 3 months building something that may not work very well and we have to maintain" - is not a reasonable premise in most scenarios.
It defies the very point of trade specialization upon literally which the economy is built.
So while we should always be learning, learning in and of itself in most instances is not a good enough reason to do something at least at work.