http://v236xhqtyullodhf26szyjepvkbv6iitrhjgrqj4avaoukebkk6n6syd.onion/t/why-does-tor-browser-use-private-browsing-should-it-change-to-normal-mode/8802
Also there is no opt-in for Cookie saving, for example for the few sites you always visit, own yourself and/or trust. This makes combined use impractical, and as said this is totally opt-in. Also: if users want to create a second profile, or simply save session and tabs in their normal one, whats wrong with that?