It's an annoying UX antipattern. It doesn't work on mobile, and forces one to use the mouse instead of just seeing the information in its more useful form.
If anything, why not put the "N days from now" text in the title attr instead?
Not every pattern that is controversial is an anti-pattern. Relative time is useful for a different reason than absolute time. One use case is not worse than the other, they're just different.
If anything, why not put the "N days from now" text in the title attr instead?