There's only like five or six true number 1 WRs in the entire league, and most don't hit FA.
What the Ravens need is like three legit NFL calibre WRs. They don't have to be world beaters, they just have to be guys that'll run their routes and make the damn catch. Hollywood is the only starting calibre NFL WR we have right now.
So for now, even if he is a bandaid solution, I would happily take Watkins. He has shown that he belongs in the starting lineup, and he's made big plays in big games. Watkins, Hollywood, and a rookie, plus a good passing game specialist could give us an efficient passing offense that doesn't vanish at playoff time.