I think that you still need good technique to play a consistent simple game. You need the right technique to consistently hit the shuttle 'effortless' aiming for the right target area.
Without the right technique the shuttle will either go out, give an unnecessary attack oppuotunity, or hitting and reaching it costs just too much energy.
Comparing simple shots to complex(trick-)shots, even with the right technique, it is more about risk/reward. A complex-shot has always a higher risk of failure but also a higher reward (speed, deception, accurate placement).
When to play a simpler game ? When you are not pressed to play a more complex game.
If you do too many unforced error or gift too many good shots to your opponent, it is time to play a more simple, robust, consistent game. If you play consistently good,safe shots without any unforced misstakes, but your opponent is like a wall returning everything (-> Momota) you need to spice up your game (higher risk->higher reward).