Being able to need doesn't mean you should. Use some common sense, if you have any.
You dont understand, I click to need because I need it
Talents (or more so, RDF role) determines what kind of items you're supposed to need. Why would a healer need tank item, healer isn't tanking now is it?
I'm joining as a tank so I don't have to wait 30 minutes for an rdf and I know the game let me need it for a item what i need, cause the game allows it.
You don't get banned for needing better items, in terms of game stats (if following rules, upgrades to off-spec would generally be against them). While you're running as a DPS with 2 x 232 ilvl trinkets, you needing a 200 ilvl trinket (with better DPS value) is considered ninja.