K.I.S.S.

•     Keep it simple, stupid
•     Keep it short and simple
•     Keep it simple & straightforward
•     Keep it smart & simple
•     Keep it simple structure
  
•     ...

The KISS principle states that: most systems work best if they are kept simple,
 so unnecessary complexity has to be avoided!

Complexity:
 Generally increases the attack surface  &   decreases the manageability.
   It quickly becomes impossible to understand/comprehend it all.
    Thus creating various blind spots.
     Which means, that the structure is no longer "under control" :-(

From Wikipedia

KISS principle

KISS, an acronym for keep it simple, stupid, is a design principle noted by the Navy in 1960.
The KISS principle states that most systems work best if they are kept simple rather than made complicated; therefore, simplicity should be a key goal in design, and unnecessary complexity should be avoided.

Variations on the phrase include: "Keep it simple, silly", "keep it short and simple", "keep it simple and straightforward",[5] "keep it small and simple", "keep it simple, soldier",[6] or "keep it simple, sailor".

The phrase has been associated with aircraft lead engineer Kelly Johnson.
The term "KISS principle" was in popular use by 1970.

The principle is exemplified by the story of Johnson handing a team of design engineers a handful of tools, with the challenge that the jet aircraft they were designing must be repairable by an average mechanic in the field under combat conditions with only these tools. Hence, the "stupid" refers to the relationship between the way things break and the sophistication available to repair them.