They come up with these configurations because of demand. That's what the buyers need and will buy. There are lots of us who need an 8' bed but many more get by just fine with a shorter one. I have the long bed in addition to a quad cab so my pickup is long and often clumsy. But, it meets my needs and I'm will to drive a long one.
We have a Dodge but when we were shopping for one in '12, the local Toyota dealer had a 4 door, long bed Tundra that we really liked. They said that they'd had it a while and wouldn't get any more because long beds wouldn't sell. But, they sure weren't willing to deal.
