it might be the underdog in terms of sales, but if it wasn't for nintendo, videogame development would come to a stall or it'd progress in a painfully slow way.. nintendo comes up with ideas, the others copy them. that's why xbox 360 has / will have access to some old games online, that's why ps3 will have tilt sensitivity on its controller. even though the console's not even out yet, it's showing the other consoles' the way already!
when nintendo designs a system, it's not like sony or microsoft.. the gamecube had NO hardware revisions so far. ps2 had a whole lot of them, and some of them had their share of problems.. xbox had a couple of versions as well, and xbox 360 is known for crashing.. so nintendo is more reliable and cheaper, which is hard to explain..