So while I agree with others you are there all this time and don’t necessarily need it there are two things that I would get them for (even if you did like 3 days park hopper and the rest without though idk if they even do that anymore).
1) on Party nights at MK, the park is not as crowded during the day. You can head there for rope drop, return to Swolphin and relax and then at night boat to DHS or Epcot for dinner
2) Connecting to what I mentioned above-minus a resort or Disney springs restaurant, let’s say you really really wanted Le Cellier for dinner….but it’s only available at 4 pm in a day you wanted to do MK because that was the BOG breakfast reservation you got. Having the park hopper helps immensely with food reservations AND if you miss something and want to go back.