That's interesting.
I recently used parsec 3. I wrote using the monadic interface because I could understand (just about) how to do so. I was looking at the examples in RWH, and I could follow the explanation of the monadic interface much easier. Perhaps this was because RWH shows how to write using the monadic interface, and then shows how to convert this to the applicative interface. It's hard to follow a tutorial that shows you how to convert from something you aren't starting with.
I suspect that this is an interesting corner case of both my two reasons – firstly, Monads are too powerful here, and secondly, you perhaps found it easier to think about the operational aspects of the parser than to think about the denotation of what the parser should parse.
Is that somewhere accurate?
I don't know. -- Colin Adams Preston Lancashire