consumers demand smaller, thinner , lighter handsets so manufacturers want to give them what they want.
compromises have to be made..
batteries still need to be charged and they still will produce heat.. those go hand in hand.
problem is now with these thinner smaller handsets everyone wants, the heat has no where to go.. so the entire handset becomes a heat-sink.
i would not call a handset that gets hot a "Defect" per se...its the nature of the beast..
great technical posts thus far however i wanted to chime in and give a different perspective amongst all of the techno-babble so as not to scare potential new users or current owners... (and i do love techno-babble)