Has there been any clock app that's useful? I find that the live tiles don't refresh quickly enough for the functionality of a clock. so the time will be right at the refresh point. and then not update until the next interval so if you look at it before the next refresh, it could be a couple minutes off.
I think they should go back to one of the prerelease designs for the Windows 8 Start screen where they had the time always in the upper right corner near your name. I think they just wanted a clean look but to me, the time should always be there.
I ended up just doing the charms swipe with a touch screen or the charms swipe with a touchpad to see the clock. That'll bring up both the charms bar and the time.
as for the bandwidth used for those apps, have you measured it? it's pretty miniscule. you could be browsing the web for half an hour and use more data than days of those listed apps.