This is by no means a defect of the device. It’s just a little contrast between the permanence of a real wifi AP and the wee little Mifi. Around the house I expect that the wifi is just always there, and so the connection, although wireless, is constant.
I went looking last weekend to find the Mifi box. I wanted to check and see if I had overlooked a USB cable. I hadn’t. According to the manifest on the side of the box Sprint doesn’t provide the micro-USB cable. I gather that Verizon does.
Rumor has it that the Mifi will operate directly attached to a host PC usng a micro-USB cable. So attached the PC powers the device resulting effectively unlimited run-time. This seems more ideal tha my present situation so I bought a micro-USB cable on E-Bay for $4 and will try this when I get home on the weekend.