A trollish or daft feedback mail can just be binned.

Yeah, and so can spam. Trollish or daft feedback still require the author to read the reply. It's still a nuisance and it disrupts the process.

feedback saying 'xyz is not really clear/your constructor syntax is difficult to follow' etc might be of help.

might be is not good enough. You might be helped by such feedback, but I certainly am not. Unless you can specify why it's not clear or difficult to follow, and what the alternatives could be, I don't know whether you simply don't know Perl very well ("not clear" and "difficult" is subjective) or perhaps you do, but you don't really know the module I wrote very well and what you think would be simpler would mean loss of functionality.

That's bad feedback, and is, IMO, worse than no feedback. It's just like questions. A wrong answer is worse than no answer at all.