The upside is less battery drain from long-distance data connections. But yes, it's not a panacea.

A neat system might be, when the reciprocation system gets more advanced, to allow for nodes to build up a reputation/trust with other nodes while they're at home sitting on charge/wifi. Then, they can 'cash in' these brownie points when they're out and about, to download stuff without reuploading anything at the time.

There are a number of ways this reputation could be represented, perhaps one possible approach might involve exchanging some unit of cryptocurrency (Filecoin?), or perhaps a web-of-trust style system where nodes publicly 'trust' other nodes based on how much use that node was to them. Personally, I think cryptocurrency is the way to go here, but there's lots of work out there on P2P incentivization strategies.

Of course, this could work in tandem with the standard barter system that bittorrent uses, IPFS is not locked into any one reciprocation algorithm and could happily use multiple different systems depending on the situation.