Wouldn't that really depend on how good your eyesight was? An anomaly might be invisible to the naked eye, or a hostile thousands of kilometers away as it opens fire (or even behind the ship).
I don't have a problem with it as a window that has displays and graphics on it, but its main function should be as viewscreen, which shows all to the Bridge staff.
Well, in Trek, for better or for worse, our standard depiction of encounters with other ships is that they are really close and large enough to be easily visible to the naked eye, and most anomalies in space give off some sort of easily seen visible indicator. Realistic? Probably not, but it's the way things work in the Trek universe.
Having said that, I don't think anyone is disputing the usefulness of an actual sensor-based viewscreen rather than a simple window. Rather, we're simply arguing that having a window of some sort available on the bridge that is not dependent on sensors could be useful in certain circumstances.