I'm perfectly happy riding my 'commuter' bikes distances of 5 to 10 miles or more. I gave up on 'sports' bikes with skinny seats and tires and dropped handlebars years ago. The average local car trip is less than 5 miles, anyway. If bikes were more comfortable and practical, more people just might take these short trips to the store or to work by bike, instead of driving....
The "commuter bikes" I tried did not feel comfortable. But I just have a preference for a more aggressive posture. I can see how some might enjoy a more upright position. The better commuter bikes also come with generator lights, easy shifting, fenders, a rack, etc., etc., etc. So you don't have to buy as much extra stuff. By contrast, my cyclo-cross bike didn't even come with pedals.
But if you like the feel of a road or mountain bike, I'd think twice before plunking down the cash for a "commuter" bike.