Come on now... I've seen some greedy decisions made in the last couple of years but this crosses the line.
The gear is attuned to the character, not the merc. You can swap gear, willy nilly, between mercs belonging to the same character.
And that is why I find it rather unnecessary. And its not even across the board, it's hit and miss in regards to which merc gear you have to attune.
Attunement exists for 1 reason: To protect crafters in the belief that if character can transfer gear in a "hand me down" process, crafters will have less to do. EQ2 did not launch with attuning. It was added quite a bit later.