The issue isn’t really that Miko can or can’t pack a punch : it’s that other characters can’t heal properly and reliably. Miko is one out of two ( from the top of my head ) characters with a potential emphasis to support through healing.
Imagine a party in, say, WoW because it’s the first that comes to mind, with a warrior, a rogue, a ranger, and a priest : well, the priest is the only one that can actually heal. He is going to get flamed for suddenly switching to Shadow to dps because it’s not fun healing or something.
It’s actually super individualist and egoistical of a Miko player to prioritize damage over heal. Or plain refuse to heal, which would be, like, never using two or three of his moves ?
It doesn’t mean he CAN’T pack a punch, it just means the reality of the game is that Miko is expected to heal and if he doesn’t, he should expect to get flamed and that’s perfectly legit. You don’t take a slot, block a character who has the very useful trait of being one of the rare healer, because you find it fun to do something else with him. If you could take more than one Miko, then I’d say please, be my guest, by all means build him the damage way. If there is an Ambra willing to heal, please too. If there’s only him, again, he should favor healing. It’s not me trying to impose my will over other players, it’s just common sense speaking and frankly, it’s how the game rolls.
In short, if a player’s intention is not to favor healing over damage when the call is made, he should take another character and leave Miko to someone that would. It’s not like there are 24 other characters available, most of them being there to exclusively deal damage or crowd control. Maybe an assassin ?
About that last paragraph, though, I totally concur! It’s one thing to demand healing, it’s another to try and protect your healer. It’s like PvP ( and even PvE frankly ) 101 ! Teamplay, symbiosis basics. You heal us, we protect you, so that we can go on wrecking stuff !