I feel it is important for both developers to spend time exploring new technologies and an employer to promote such culture. The latter I think falls under the Innovator's Dilemma.
It is important for a developer to explore new ideology and technologies and way of doing things do add to their own confidence in choosing a particular technology/method over another.
But should a company promote something not directly linked to its working and not adding to it's growth? Is it fair to compensate for something which is not benefitting the company in return?
If it does not let its developers innovate, it might face disruption in terms of technology or adoption. And it risks the loss of faith of employees. People who are highly motivated will continue to work on personal projects and will eventually move a organisation where such endeavours are encouraged. This is not a doomsday scenario but just one of the many things people want to work at a particular place. Personal development is a big plus!