because for some it's a deadly obsession. they like to track each %.
i deleted all battery % widgets long ago and i suggest that everyone do the same. the battery % is not accurate and it's silly to sit and watch every % and extrapolate when the battery % consumption is not linear and constantly worry about the battery. my advice is to just look at the default battery bar and stop stressing about the battery. just relax and enjoy and use the phone and stop obsessing about every misreported incorrect battery %. you will have a little less stress in your life.
Lol. Plus the widget would be using juice as well, right? Lol