The thing is, you are not shoehorned into any bit of content. Maybe by your guild, but not by the game. This same guild would force you to do archeology all day if that gave more AP.
Islands were designed to be the most efficient AP farming methods, this is their purpose beyond transmogs and pets or whatnot. M+ give actual loot. Huge difference. By your logic Islands would also need to provide loot in order to give that "variety" you want. Which would infintely inflate item level given their easier design.
Your solution to the problem is basically just flipping it, making Islands completely useless. Why would you farm islands for AP when you get the same + loot in M+? This is not a solution. This is not a problem in the first place.