Burton K Wheeler
Moderator
Basically this. With Harriers, you can operate pretty much anywhere. Throw down some steel planks or mats, chopper in a few fuel bladders and ammo and you've got a forward operating base set up in a couple hours. No need for long airfields like you'd have to have with Skyhawks or Corsairs.
Or specially treated concrete like you need with F-35Bs.
Why did the Marines not replace the A-4 with the A-7 when the Navy did? Holding out for Harriers? Or did they prefer the short-runway ability of the Skyhawk?