Maxist said:
Is it better to do things that are primitive and simple, but effective, or very very complex on many levels, but not as effective as the alternative.
You've already chosen the answer you're going to get by the way you phrased the question.
Provided that the only two variables are simplicity vs. complexity and effective vs. less effective, the simpler
& more effective method is preferable.
One of the main reasons to increase complexity is to also increase effectiveness. Even then, we frequently need to ensure that the increase in effectiveness justifies the increase in complexity.
However, there may be other factors ... like additional consequences.
For example, when it comes to conflict resolution, violence is primitive and effective. Mediation is more complex and a lot less effective (in the short term). However, violence has a number of unfortunate consequences (like retaliation) which are not associated with mediation.