Many people travel from Bracknell to Ascot to make connections with trains to Guildford. It's a shame that there are no direct trains from Bracknell to the Guildford branch, it seems to be a very viable route, and doesn't require much effort to introduce.
It may sound like it doesnt require much effort, however in reality it would be potentially more effort than its worth, particularly as the reading to waterloo line already suffers from poor reliability. The service would require a reversal at ascot, which is is a hassle just for the train to continue 1 or 2 stops to bracknell. Also, at bracknell, and between ascot and bracknell the service would take up precious paths for the waterloo trains, which could result in decreased reliability, particularly as there is potential for a 4tph service to be introduced in the future.
Peter is correct, I do not think this is something that is likely to happen any time soon.