I think you're accidentally conducting a motte and bailey fallacy here.

It's making an ambitious risky claim (make things simpler than you think they need to be) then retreating on pushback to a much safer claim (the all-encompassing "simplest thing possible")

The statement ultimately becomes meaningless because any interrogation can get waved away with "well I didn't mean as simple as that."

But nobody ever thinks their solution is more complex than necessary. The hard part is deciding what is necessary, not whether we should be complex.