The basic problem is that https sessions are opaque as they travel through the network. That's the point -- it's more secure -- but it also means that the network can't do anything about them. They can't be compressed, cached, or otherwise optimized.
Schneier on Security: Man-in-the-Middle Attacks Against Browser Encryption
Mon avis à moi? On va finir par généraliser le MITM d'infra
et chiffrer les données (sur la couche 8)