This is absolutley not women's fault or problem but if you are unattractive even hinting slightly that you like a person will be interpreted as being creepy. Outside of work you can accept the rejection right away and move on, at work, rumors will ruin you. I don't know about others but no romantic opportunity is worth sacrificing a career.
For me it isn't even just all that but making someone uncomfortable at their work place where they have to work with you everyday sounds like a horrible thing to do. What if they view you as an authority figure or feel like their rejection could affect their career/work? This is even before HR and managers get involved and you get a nice public humiliation. I mean, don't eat where you shit, right? There is plenty of other places better suited than work.