so, you want all fight become tank and spank, with no mechanics, no necessity of positioning and so on?
Come now, no one said that. In fact, creating interesting mechanics that do not excessively punish melee DPS wouldn't really be that hard. Leaving a "safe zone" in the damage area, like cleaves instead of bursts, or if the AoE is intended to create a healing complication, make it unlimited range. Making the movement instigation something that pops up under people's feet and can affect melee and ranged equally (though this can be excessively punishing to Melee DPS if they hit a string of RNG bad-luck and suddenly the boss is surrounded by zones of damage).
The point is that it's probably pretty easy to focus on mechanics which don't naturally disadvantage DPS players, but because the burst AoE centered on the boss is such a trope of the genre, it keeps worming it's way into every game. Leaving out that one mechanic will not make all fights tank and spank.