Unfortunately clients or designers have these because they look nice, add some drama to a page, or because a competitor has one. So it really comes down to the goal of page (conversions, branding, SEO dwell time, etc.)
It has been in alpha for like 3 years now and still no clear sign of a release. However, I still find Bootstrap highly invaluable for knocking a quick idea together. The best thing about Bootstrap is its grid, it's easy and quite powerful (especially in BS4).
BS 3 is still very valuable for responsive-site conventions within a team, especially if you use it 'properly' from Sass or LESS source. The main part looking dated at this point is the JS that still relies on jQuery. There're projects like boostrap.native [1] and e.g. ReactBootstrap to deal with that tho.
I'm in no hurry for BS 4 until IE (< Edge) completely dies.
