It's not a problem inspecting peoples gear/IO after you get invited to the party - obviously I'd expect everyone to do a quick inspection of the party before starting the run. It is annoying having no idea what the party members are like before you get invited.
I'm not really talking about myself though - I'm a relatively high rated/geared healer, it takes me minutes to get in to groups.
I was speaking on behalf of hypothetical DPS players, who might spend ages and ages queueing to get into runs, finally getting accepted, to find out that half the group is in levelling gear. Sure they can immediately leave, but it seems like a clunky way to do things.