As shown in the title of this thread, I am running Kitkat 4.4.2 on my Droid Maxx. I don't believe this is a bug. I believe Google removed the USB OTG feature from Kitkat 4.4 to make us more cloud dependent. If it's fixed on the Moto X with Kitkat 4.4.2, then why not the Maxx? Whatever Google giveth, Google taketh away!
4.4.2 has not been delivered to the Droid Maxx yet. The 19.6.3 update is still version 4.4. You can check for yourself in settings / about phone - you'll see that it's just 4.4 still. The latest OTA was mainly an update to the baseband to correct a rare roaming issue in Canada, as well as turning the status bar icons from Holo blue to KitKat white.
FWIW, the Maxx never had version 4.3, either. It went from 4.2.2 to 4.4. (There were two OTAs, one at launch in August and one in November, that kept version 4.2.2 and now two OTAs that have been 4.4.)
Again, I don't know that 4.4.2 (and it is confirmed to be coming from sources at Motorola, though there is no promised timeframe) will fix the OTG issue, but it did on the Moto X when that problem happened when that phone got 4.4 with a nearly identical build as our phones. The same thing happened to the Moto G when it was updated to 4.4, and OTG support was fixed in 4.4.2.
See
https://plus.google.com/102838570385793445288/posts/Dfpjj3F2K6T for more about this and the coming 4.4.2 update.
And, just to clarify this some more, USB OTG support was an undocumented feature that just happened to work. Motorola never advertised that these phones supported that feature for attached storage. Still, I hope that the experience of the Moto X and the Moto G is a hint of what will happen with the Droids - though that may not be so.
(Also, iOS definitely does not support USB OTG unless except for the import of photos, as far as I know, so switching to an iPhone won't help you there.)
I will say this: I share your frustration with the delayed 4.4.2 update. This phone has had several bugs introduced with the 4.4 update in December/January - the OTG non-support, the double home key problem, the share bug, with the share menu getting stuck to one share item - and it's coming on five months with no resolution to these problems. I understand that there are time constraints, etc., but it would be nice if Verizon could be more forthcoming about acknowledging these bugs/issues and giving even an estimated update schedule.