Using disconnect's proxy? Looks like a trap to me. Give me proof, you discard all the data, then we are talking. Otherwise this approach is mostly flawed.
If I recall correctly the standard MacBook Pro also sports a DVD-slot drive, which may attribute to quite a bit of the added weight and size. However I do agree, that modularity will come at the prize of less miniaturization. And with mobile phones this is even more of an issue.