No. Intentionally, we are maximizing the use of quick match and making the online play system the simplest and most elegant thing it can be. You can click quick match and get a match, or you can directly challenge a friend. Directly challenging a friend intentionally does not use any sort of lobby UI, and instead simulates exactly what the UI looks like when you are sitting next to your friend in local play. Custom rooms just take away from quick match, so we do not plan to create them. Incidentally, Hearthstone does the same thing.
That said, spectating will be supported. When you go to your friends list, right now there is a crossed swords icon next to each friend that lets you challenge them. If they are already playing, they aren’t challengeable, and the swords will change to an eyeball. You’ll be able to click that to spectate and doing this will automatically follow them from game to game (no need to click the eyeball again as they go from match to match). They’ll also be able to invite you to spectate them.