When you implement an equality operator, or addition/multiplication operators on a type there are 'laws' too, but that doesn't stop it coming down to 'has an equals method'.

Then why not have both? Applicative Functors have both `fmap` and `<$>`. `>>=` could easily be an alias of `flatMap` or `bind` or whatever.

I'm right there with you. I'm a Haskell user; I love user-definable operators.

Because code is read more than it's written; multiple ways of writing the same thing makes it easier to write but harder to read.

Multiple ways of writing the same thing makes it easier to read, often, because you are more free to use the form that is more readable and intuitive in context; that's one reason why natural languages (including written languages) tend to have multiple ways of expressing the same ideas.