Well the value of best shares history comes to the fore when someone mines solo (like I do) cause it helps to understand whether all your large shares got to solve the block. It helps to understand if your pool is working fine. Cause if you've had like 4 shares with bigger value then the current network difficulty but got only 3 blocks then you should check what went wrong on the pool side.
If it's not difficult to implement then it would be nice to have that.