I consider myself a Haskell beginner, and I think that the current situation (with the use of fromList) will be less confusing than the funny brackets.
Even if you could make it so that copy/past would turn funny brackets into fromList, it would still be surprising behavior. When the code does something unexpected, we are going to try to put in the funny brackets in the repl. (Maybe that's more for programming beginners versus Haskell beginners, but let's not discount them either).
I haven't read the docs, and I understand that your primary concern is the noise from
fromList, but I think leaving things as is and adding some wording that says "Hey, if you want to avoid having
fromList everywhere in your own code, you can add OverloadedList extension" would be the most approachable. (Shouldn't be too much to ask a beginner to at least read the preamble of a module's docs).
Just my 2 cents.