The reason I call is because I've been told by at least one MS CM that the request I made is "not in the list". For example, at AKV I like to request "lowest floor". I've been told that MS's request list includes "high floor" but not "low floor" or "ground floor". I like to make sure that they will type it in and that what they typed hasn't changed the request into something I didn't intend.
It's unfortunate that we're not able to make and view requests (both drop down selections and typed comments) on our reservations online because that would greatly reduce these types of phone calls to MS.