It’s an interesting linguistic observation: sometimes you ask the question “What for?” but you get the answer suitable for the question Why?
The Why? is about the past. It refers to the reason, the to circumstances that are already taking place and have already affected the decision made.
The What for? is about the future, about the purpose. It claims something that does not exist now but will be there (if we do it right).
The <…> was done
because of <existing_limitations>.
— vs. —
in order to <future_plans>.
This does not make either concept better than the other one. They are just different by nature and should be used differently.
👉Tip
Emphasizing the “What for?” helps the team to clearly see the goal, either upcoming short-term one, like a Sprint Goal, or something bigger like a whole product purpose.
The “Why?” plays main roles during post-mortems, retros, etc. With some practice it renders the process bottlenecks visible.
❗ Be careful with the “Why?” because it might sound blaming. It shouldn’t be about the blaming but about improving.
A minute of linguistic.
German and Dutch languages use the words “warum” / “waarom”. Despite of both don’t distinguish the “why?” ↔ ”what for?”, I like the formula
warum → um zu ... or waarom → om te ...
which explicitly means the purpose.