Well, it seems so to me. OUAT is derived from Disney versions of fairy-tale characters. SHIELD does strike me as odd, too, but it's derived from a hyper-successful theatrical movie. But an ongoing alternate universe story about losing the Revolutionary War? Definitely an odd choice for a mainstream network.
I think the other major factor that makes OUAT and SHIELD not be so strange for ABC is that Disney owns ABC and Disney owns Marvel.
It makes sense that they would make use of properties they own to fill programming on the major broadcast network they own. It also keeps those brands in the public eye more to generate interest for other ventures set in those universes or using characters/themes from them.
Once Disney bought LucasFilms it pretty much became almost guaranteed that if a live action series set in the Star Wars unvierse happened it would be on ABC (and about a month ago stories did come out that ABC was in talks for such a series).