Haha :D. Well, let me try :to do this in this comment for you :).

Here are some potential bullet points you can use, try to make it hit the emotional spot, not the logical one (I know my article is more logical :) )

• Getting smaller and more "portabe" sleeping space allows you to do yoga in the morning, or have kids on the futon/mattress without the fear of them falling, or have additional space for your hobby
• Having smaller bed or bed closer to the ground allows more cuddling and more fun
• It is way cheaper so we can go and buy that flower into the garden you wanted for two years.
  Just some ideas :) Hope it helps.

And thank you :).