I love the way Miko is actually designed even as a pure support. This game has many type of support
Heal support (Miko)
Zone & Shield support (Kleese)
Duo support (Reyna)
…Damage support (Ambra)
Miko is fine doing his role as a healer. The issue I really have with him though is how tanky he can be while being faster and harder to hit than most chars in the game because of the small model. Marquis, Ambra are also similiar example of what suffers from the “I’m not that squishy cause my base health/shield are great but I’m also super fast with very small model” issues. Even if you want to kill them, you can’t land most of the hit like you do against Reyna or even land ALL of them on Kleese.
Miko’s survivability certain needs to be looked into more than his healing power. “Heal Thyself” with his self-heal active with +healing stuffs are BS when combined. Add in Fight-or-flight and Miko becomes one of the hardest char to kill especially in a game where the DPS is quite low unless you pick the top tier char. Most chars DPS are just so bad outside casting skills.