I think it's because the old imp ping system hasn't been changed.
Because the old pings where a lot better and easier to see and lasted longer it was fine in previous seasons but they adjusted what the pings look like without changing how the imps ping to suit the new pings.
Was managable just had to make sure you had map open before imps started. But unless they want players the be that alert (which could be fine for higher lvl players) could be made easier.