Strategy means more time invested in order to win. It means utilizing things like lockers (many enemies), fight mechanics (think: Shushu II Totem heal mechanic), and knowledge of enemy spells (think: Cavliew only being able to jump to you when linear within four range) to their maximum counter. It's means not mindlessly nuking the enemy to death a few turn cycles.
This [strategy], unfortunately, yields no grandiose rewards, hence why you want less strategy and more mindless nuking to achieve what you want, faster. Challenges are a means to slow down the player to make them want to work harder to spend more time to achieve said reward, however even then the challenges are either completed with little to no effort (yielding a marginal reward for basically no time lost), aren't worth it at all, or are basically impossible to complete.
Sadida and other classes such as Pandawa fit well into the niche of complex strategies, but do not fit the niche well of high damage and overpoweredness to the point of rendering strategy moot when you can DPT the content to death in an instant. This is relative to the other big players of the DPT league (Iop, Rogue, Xelor, etcetera). Obviously with the correct gear, any class can put out respectable numbers. Some just do it far better than others.
But ultimately it's the same concept as high powered players beating content in other games (e.g. fighting content lower leveled than you) and applied to class balance.
It's a very redundant and obvious belief, but it applies to this game very well.
Speak well or just play silently.