Currently when using the keyword difficulty tool there is a limit of 5 keywords per request. Getting this data out of the KWD Tool into a spreadsheet, especially for large keyword lists, is highly manual work.
Having the ability to automate this would be hugely beneficial. I figure this means adding this service into an SEOmoz API.
It would save time doing menial legwork.
It means we can get information for all of the keywords we are interested in.
It means we can all of the data as one 'snapshot in time' - sometimes for large lists, the data can change over the course of a couple of weeks it takes to complete the list, so making relative comparisons is skewed incorrectly.