Show unimplemented cards as playable?

From #9103 discussion.

There are possible to add unimplemented cards as simple/bulk card, so users can add it to deck, play and do all other things. It can be simple colored creature or land card with additional rules about unimplemented feature.

One of the annoying thing in current version -- if you download new deck with unimplemented card then you must edit deck and replace it with another existing card.

So is a playable unimplemented cards can be useful?