Best is to make things optional, a way to turn it off
It could also be possible to display it smaller for people with small screen (thanks to the gui system). Another way would be to show the hp/shield when it's changing and hide it once it's full. I don't think the size is a problem, the problem is when the screen is filled with unneccessary stuff. Better to display things bigger, but display only stuff that is important, and put other stuff in menus.