OP You really should have asked before taking the pictures. As another poster found on UA site which is pretty much industry standard you cannot take pictures like you described. If any crew member was in the picture or any passenger for that matter and you did not ask their permission, that person has every right to ask you to delete the photos and also has every right to contact the authorities to have it deleted if you don't comply.
You said you were inflight you would have had to ask all passengers within the shot for there permission.

As for the F/A's attitude I can understand why, you didn't ask and the F/A's don't know what manner you will use the photos. We get memos and training on what has been done with such photos and it is scary. I know my company doesn't allow it and I enforce it too.

If I were you I would really think twice next time and ask.