Yeah, I just can't see wearing a watch underwater to tell the time if you are already wearing a dive computer (which also tells the time).
Really, on your dive you should be focused on bottom time, not on what time it is. Although I admit I have looked at that when someone is waiting for me topside to get dinner!
As far as redundancy, if you are diving in situations where you need a backup timer (say, a dive with a deco obligation), you might as well get a bottom timer as backup for your dive computer, as opposed to a watch and an analog depth gauge. Or better yet, a second dive computer, which you can probably get for less than a bottom timer, and just use in gauge mode.
Really, on your dive you should be focused on bottom time, not on what time it is. Although I admit I have looked at that when someone is waiting for me topside to get dinner!
As far as redundancy, if you are diving in situations where you need a backup timer (say, a dive with a deco obligation), you might as well get a bottom timer as backup for your dive computer, as opposed to a watch and an analog depth gauge. Or better yet, a second dive computer, which you can probably get for less than a bottom timer, and just use in gauge mode.