Blame the pictures of classic Nightwing and 514A for this starter.

" I actually decided to let it grow out despite Alfred's complaints, not really trying to control it. I had the idea to let it get unruly  from Selina and her curls.. But I'm making sure it'll never get in my eyes when I fight, or when I fall. " Bruce explained when you saw the change in his hair style, " I actually had to put in a lot of work, treatment for it before, for years wasting my time. Every morning for me was like being a bird having it's feathers plucked out or dunked in oil.. But this is freeing, natural..  It's never going back to that style, being cut like before and I won't regret it. Not as Nightwing, not as Bruce Wayne."