If you look at the whole cycling deal, many want to hang on to a bike design that was invented in 1890. While a modified version of it is great for single tracking and mountain biking, some of the negatives of that design suggest we should move on to newer and better designs. The main drawback of the pure diamond frame design is the tiny seat that DOES cause pain in the rump, no matter how much a small group of nay sayers claim it doesnt. The other is the fact to go faster riders jack the seat way up and put the handle bars way down. That causes two problems, first is the rider is bent clear over compressing his chest area limiting his breathing ability. Second it puts the rider in such a head down position that it is hard to see where he is going, which means he ends up staring at his front wheel much of the time.
So we come to recumbents, both bikes and trikes. They too have their own drawbacks. First the LWB bent are so long they are somewhat problematic to transport for their size, and the SWB are somewhat difficult to get used to riding with the feet so high off the ground. The drawback of trikes are of course their width.
Then of course comes to the advantages of recumbents. Fully open seating means full lungs for breathing. It also means setting upright gives the rider full 180 view plus. The comfort of setting on a large seat is of course a given. Trikes have their given of no tipping over, no need to unclip when stopped, and no need to find something to lean it against. Both bent and trikes have a more aero profile for reduced wind resistance for faster riding if that is what you want.
For the reasons above recumbent bikes and trikes are the modern alternative to the 1890 DF bike. Too many people keep hanging on to the antique design where it is not needed IMO. Casual riders would be far better served if they rode some form of a bent, for the number one reason, no pain.