Whoo.. speculation central. Gotta love dem airsoft chinese whispers.
As is the story with so many carbine variants of issued rifles created throughout the last 100 years or so, there was a need for a compact weapon for aircrew, armoured vehicle crew etc. Something that had better range, accuracy, handling characteristics and magazine/ammo compatibility & capacity vs a 9mm pistol or sub-machine gun, while also being super compact (even more so than a 10.5" barreled M4). Funnily enough this is something our military has done well at over the years, many aircrew used to be issued the HK53 with the sliding stock which does collapse down extremely small yet being 556 with 30 round mags actually gives you a fighting chance against people with conventional military rifles. Then of course there's the L22 which has a much longer barrel than the HK53 (meaning better accuracy and muzzle velocity), is even more compact and takes the same mags as everyone else around you would be carrying.
I'm not sure whether the DoD actually put out any sort of contract or initiated a competition or set of trials for crewman PDW, but Magpul Industries unveiled the PDR back in 2006. Uses the conventional NATO standard for magazines and ammo in an extremely compact rifle which still maintains a long enough barrel for the 556 round to develop an effective muzzle velocity (along with numerous other advantages compared to an SMG).
Magpul Industries stopped working on it around '11 (probably no military interest) but as with the FMG/FPG before it a couple of employees carried on with finalising the external design, working together with PTS to bring the airsoft version to market. Personally I think they f'd up by coming out with the PDR-C rather than the PDR-D because the latter has some 20mm up front for modularity, a proper pistol grip and a physical selector/safety switch (one or the other).
Aesthetics... well that's about the most subjective thing in the world. The firearm itself has some shortfalls but it does the job it was designed for despite the long list of restrictions and limitations. Airsofters mostly live in a world based on guns dreamt up in the 40s and 50s, and for some reason despite most people being obsessed by 'the latest thing' in pretty much every aspect of life we're entirely stick-in-the-mud about weaponry. Not saying it's wrong to like AKMs or whatever, you can shoot BBs through whatever shaped toy you like on the weekend. Just saying that technology has moved on and when you look in to current design work you'll see the PDR actually doesn't look like a space raygun, it looks like a gun from 'today', perceptions are just skewed by the prevalence of very very old systems. A laptop or tablet would look ridiculously futuristic if everyone still had a dedicated room full to the rafters of whirring reels of tape as their home computers, but they don't, so it doesn't.