I still believe Moto is at least partly to blame for putting a single antenna in a flagship device.
S5 tap'n
I hear you and I appreciate the opinion, however I don't believe that was Motorola's decision. Remember, this isn't JUST a Motorola device. In fact it's more a Verizon device in many ways than a Motorola device. It's a Droid. The Droid name is a registered trademark of Lucasfilm, Ltd. and licensed to Verizon. Since Verizon pays the licensing fees they own the Droid line of phones. They then likely contract Motorola (or in the past other manufacturers), to either make phones of a certain style, or decide which of the phones already in development will fit the moniker, and then specify features and software implementation to their own demands. In effect, Motorola is acting as a custom manufacturer for Verizon and Verizon calls the shots.
Verizon is anxious to move as much of its cellular data/voice communications over to LTE/VOLTE as possible, with the continuing efforts to advance the network towards LTE5 (5G). They are expected to continue providing CDMA 1X & EV-DO as well as 2G/3G service through 2021, yet this will be mainly to provide ongoing support for connected devices (think cars, shipping containers, industrial equipment and even vending machines and jukeboxes, all of which will need a network to link to), and not primarily for smartphone communications.
So Verizon would have mandated the removal of the dual antenna configuration on this new line of phones to reduce its impact on their networks and eliminate the need to run two connections at once to support simultaneous voice and data out (SVDO). By reducing the number of channels that a phone needs from two to one fit the same functionality they cut costs by potentially hundreds of millions of dollars per month in operational expense. Total operating revenues in second-quarter 2014 alone were $31.5 billion, with 104.6 million retail connections. Take that number of connections and let's be conservative and say half are not phones, and then that half again are not smartphones. So upwards of 25 million phones or more, until the introduction of VOLTE, using two network paths at once to communicate SVDO, and that spells a great expense.
Again, this is not Motorola's fault IMHO, although one could argue that Motorola may not be placing as great an emphasis on upgrading the Verizon branded phones as they are their own (think Nexus 6, Moto X, etc.), simply because the Droid line of phones is a small slice (comparably), of the total cellular phone business they do, most of which is not custom branded and custom manufactured. And lastly, because this Droid Turbo is the first Droid phone to not have the dual antenna/dual radio capability of earlier phones, it becomes the problem offspring for Motorola where Verizon is it's legal mother and guardian and therefore sets the ground rules, even though Motorola is it's biological father.
And to answer (again, my opinion), your question about why just Motorola? Well perhaps because Motorola may have been the least averse to making the latest lines of Droid phones, as opposed to HTC or Samsung or someone else. Samsung likely didn't want to do it because they are pushing brand recognition and their own line of phones (successfully) hard to compete head to head with the iPhone. HTC is struggling to maintain its brand, LG is pushing hard to carve a slice out of the pie, and the rest are more likely to get marketshare and build brands more effectively by maintaining zero dilution.