Funny that you mention that, I thought the same until I discovered various websites offering remuxed trailers for hundreds of movies with lossless video and/or audio streams. I since decided to have Kodi play these with MPC-BE for highest possible quality.Yes. I don't think anyone wants to open a trailer for example with anything except the Kodi internal VideoPlayer.
My Harmony 900 is also mapped for commands using hard and soft buttons. I find it easiest to map the soft buttons because you can label them and they are plentiful. For hard buttons I spent a lot of time figuring out common map codes between all the different players. For example: Instead of having multiple mapped codes for "menu" for each player, I found a code common to all/most of them. Then I simply use the 'menu' hard button and they all react to it depending what is in focus. This way the Kodi menu doesn't open when MPC-BE is in focus. Only the menu for MPC-BE does. Likewise, when Kodi is in focus, pressing 'menu' opens the Kodi context menu as it should. I listed them long ago in my thread in the link provided in my sig for anyone interested.
I really should experiment with soft button mapping as I tend to forget what some of the physical buttons do after a while of inactivity..