There are so many different (and contradictory) legends behind both Robin Hood and Arthur that there is no such thing as the "definitive" version of either. Every version out there is one person's interpretation.
The goal behind a re-envisioning shouldn't be to simply make a new film/series, but to tell a certain story or moral about that character. If the CW wants to make a series about Robin Hood, great. Just have a reason for doing it.
I was one of those who watched Smallville back on the WB, but after around season 5 or so it started to wear a little thin. It stopped being about telling the story of Clark growing up and coming to terms with his heritage, and started being about the CW trying to desperately cling to ratings using an aging tentpole.