Wow, like many of the others on this thread, I, whom apparently had a long forgotten account for these forums, had to go dig it up and recover my password so I could come here and post, because this issue was simply too frustrating to ignore.
The awesome level of frustration this change inspires seems more suited to verse, but since I am (fortunately) not a poet, I guess I should instead just tell you a story.
There I was, 200 dwellers, 97% happiness, innumerable rare items (yet, somehow, still not a single legendary recovered from the wasteland....). I had 86 dwellers in the wasteland, a number soon to be much higher as I had 30 more slated to reach max SPECIAL within the next couple days, ready to send out exploring on a 5-6 day long rotation with the rest. My vault was running at near maximum efficiency, needing fewer than 100 dwellers to keep operating, despite my massive appetite for stimpacks to take on wasteland expeditions. By this point in the game, the only thing still worth doing at this stage in the game, and the only thing that kept me playing, was sending more and more dwellers into the wasteland, collecting more and better outfits in the hopes of one day landing some legendary gear. With 80+ dwellers in the wasteland, there was some minor performance difficulties experienced scrolling through eaach of them to track their progress and tell them when to return... but it was a sacrifice for the greater good! I was prepared to go all the way, 110+ dwellers of performance-draining explorational goodness, to meet my goal.
I had just sent about 20 more out again on a fresh run the night before when I booted up my game to find... an update! I started by checking my dwellers in the wasteland... revived a couple that had died and told them to return home, turned back a few more with 0 stim packs remaining... wait, what's this? a legendary armor? 4 legendary weapons? Was it perhaps a bug all this time that was preventing me from getting legendary items, and bethesda had finally fixed it, allowing me to collect? Huzzah! Perhaps the bethesda folsk were competent after all! Although this left some questions about why the bug was there to begin with.... Now just to collect a few dwellers and send them back out again... but no.
I couldn't send them out! I now had 75 dwellers in the wasteland and 11 wandering around uselessly on coffee breaks, and couldn't do anything about it. How many did I need to bring back in before I could send more out again? 1? 26? Throughout the day I kept collecting returned dwellers a few at a time as they trickled back... It was when I hit 49 in the wasteland and still couldn't send any out that I snapped. This is rediculous! What's this new maximum number, and why is it so low?
I checked the forum and my heart sank. TEN!? The maximum dwellers in the wasteland is TEN!? WHAT!? How could anyone think this was a good idea!? What am I supposed to do with these LITERAL HUNDRED DWELLERS all specced out for exploration, now with nothing to do? and more importantly, what was even the point of playing the game now? No more meaningful exploration means no more game. That's it. I'm done.
RIP Fallout Shelter, you were fun while you lasted.