I don't mind multiple characters on single hard nodes. I loved it when this game was just starting out and you had to choose which characters to farm - because you couldn't farm then all at the same time. If someone wants to whale it up and have every character at seven stars quickly, there is a vehicle for that.
Perhaps a nice bone to throw us would be to stick one of these characters in the shard shop briefly - for some extra shards at the expense of some gear farming. This happened a little bit when the shop first opened.
