Starting with Vista, Windows has had, by default, an automated defrag that is more than adequate (with XP and earlier, I'd actually run 3rd party defrag software). I'm sure a majority of users don't even realize its at work and likely have even forgotten about disk fragmentation and thus forgotten about defragging as well.
I don't defragment my SSD just my HDD every one in a while using the built in Windows Defragmenter.
I turn off all the scheduled defrag bullshit in Windows though. I want to defragment when I WANT to
there's little serious reason for 99+% of Windows users (at least Vista and beyond) to not just let the OS take care of its own defragging
1. SSDs don't need it and technically
shouldn't be defragged, and Windows won't defrag SSDs by default
2. the automated defrag is smart enough to not run when it would be a detriment to the use of the computer
3. by letting automated defrag do its thing, its pretty much a guarantee that there will never be a drive that is fragmented enough to require any sort of lengthy defrag time in the first place