An extreme customer service option
While some people will welcome these devices as a godsend, others will resent the idea that they have to spend anything extra to get cellphone service they are already paying for.
Plus, when you make calls while your phone is connected to the MicroCell, you are still using up the minutes in your AT&T plan, just as you would on a regular outside tower, unless you buy an optional extra-cost MicroCell service plan. The company defends this by noting that you are still using its network, even though you are connected to it differently.
However, at least two of the carriers—AT&T and Sprint—are quietly giving away these devices to selected customers with terrible coverage whose patronage they presumably wish to keep. It is unclear to me how to qualify for these free devices, which appear to be handed out on a case-by-case basis.