Unlicense or WTFPL license is more permissive and will make Godot even more free (as in freedom) and open source, so Godot should stick to Unlicense or WTFPL.
Off course I am not suggesting that people should not give credits to Godot. I personally would give credits regardless of what license it uses and I don't encourage anyone to be a dick about it and not give credits to other hard working people.
What I am trying to suggest is that when you download the software, the copy that you downloaded should be yours right? Placing any kinds of restrictions gives a sense of that you don't own anything.
If you disagree with me please kindly let me know instead of marking me down.