My "junk food" in this case is beer, whisky, pizza, chips, and bad comedy movies. I enjoy them all greatly. Food can be a visceral pleasure and I can derive as much or more from a crappy pizza as I can from a gourmet meal. So... my "junk food" really is a lot of junk food. Yours or others may not be. Also YMMV.
Going quasi-paleo, I learned how food is supposed to taste, and everything tasted better. Junk food also tasted better. Way better. Crazy better. Years later, I still remember 1/6 of a pretty basic Safeway chocolate donut tasted, and what I was doing at the time (physics club). It was the first junk I had had in months.
On the other hand, my life would have been perfectly enjoyable without it as well. A link between junk food and enjoyment... I'm not going to judge it, but I'll say life's better when that link doesn't exist. When my life was nothing but junk food, nothing really tasted good. It was all just bland; like I was feeding a habit more than having a treat. Junk food was an escape from life for me, because life sucked. In part, it was not under my control. But in maybe the greater part, it was, and junk food was one thing I used to avoid having to do anything about it and still feel 'ok'.
As far as time, if you're eating well, planning ahead is key. You don't need junk food to help you get things ready faster, because you've already cut up some fruits and veggies for snacks, or you've got a bit of last night's steak for part of your breakfast.
> And then some junk food, because life is for the living and you have to find some time for enjoyment as well.
Interesting how enjoyment is connected to junk food.