I don't have any strict objections, but I think we would need to see demand for it. An individual's /rank can already get pretty complex if they have a lot of formats - adding another column of "Reset W/L" would make it even more cumbersome. I doubt people are resetting win/loss records so frequently that this warrants handling it from the simulator itself. Perhaps run a Showdown room poll and see what the results are?
I also think the inconvenience is in part a good thing. When it's behind the userpage, it's much less likely you'll misclick or something and accidentally reset your win/loss record. However, you could probably do a straightforward "are you sure you want to do this" confirmation prompt to ease that issue.