In my view, utility riding and commuting goes best when you get the most speed you can out of your effort. If you're going to be riding on paved roads, then, a road bike built for speed is the starting point. Compromises should be made to that design only as needed for other things.
I use racks and panniers, on the front and the rear. This set-up is more than most people would need for commuting alone, but all of this carrying capacity comes in handy for grocery shopping and other errands. So, from a road bike, I move to a tourer. A tourer has a longer wheelbase, and so makes the addition of rear racks and bags more straightforward. And, of course, a tourer is set up to mount a rack and bags on the front.
I add fenders, a kickstand, lights, and some sort of crank-guard to protect regular pants. These things don't require any special bicycle design, though.
A tourer is as far away from a road bike as I need to go, though. The european-style utility bikes tend to be too casual in their geometry, for my tastes, despite their many other nice features. Mountain bikes, and their urban variants, have much fatter tires than is needed to ride on paved roads. The suspension is not necessary for road riding, but it's heavy and it kills some energy. (If real mountain biking can be done without suspension, and it used to be done that way all the time, riding a fat-tired bicycle on a paved road can certainly be done without suspension.) Disk brakes aren't necessary, either, though perhaps they would be better in very hilly or mountainous terrain.
Efficient riding on the pavement has long ago been worked out by bike designers, in other words. Vast improvement certainly does not await the application of off-road technologies.
So, a touring bike is, in my view, the best utility bike. Most people who use mountain bikes would be better served with a tourer.
All that said, if your commute is only seven miles, and you've got a good bike set-up now, you wouldn't find it's worth a lot of money to make a change. You would go faster on a road bike, to be sure. But on a seven-mile commute you would save only a handful of minutes, at best. A good bike that works for commuting is no small thing, and you have that already. So, it's likely the cost of a more suitable bike would outweigh the benefits to you in your commuting.