The Mister Handy is a great idea. But it suffer from another new feature, the Deathclaws. I'll explain this in details :
? Before, a player may put 2 gardians at the entrance of his Vault, and if they had great weapons (having both 20 or more damage power), the thiefs would never go into another room. Meaning that the player could just leave the game for a few minutes on without having to be scared of an attack.
? The Mister Handy would come in... handy there, since he could actually allow the player to continue to do so even more, since the player who would use it could just "heal" and "play" the game without having to collect. The player could, basically, play for hours and keep doing other things at the same time.
? But the Deathclaws changes everything. Now a player will open, collect, and then quit the game quickly, as the fear of staying online and being attack by the Deathclaws will forbid anyone to keep the game open more than necessary on their device, especially if they can't heal the dweller in case of attack. Meaning that the player won't pay for Mister Handys, as it is useless if the player doesn't keep the game open, and also made useless by the fact that the ressources obtained by the Handy Man will actually be stollen/eaten by the Deathclaws.
Now I know some of you actually paid for them, I would too. But if you can't keep the game open almost all the times anymore, they are a lot less usefull than they could have been before.
Like I just said, no you can't since your dwellers would be annihilated by Deathclaws and other dangers... But Mostly deathclaws.