The fact that we suddenly have a boatload of free weather data? Nobody installed any weather stations - this is information fallout being put to good use. That's pretty awesome.
> This is a well-known fact to all people working in semiconductor industry and we simulate things against temp. all the time.
Simulating how an electronic circuit works under different temperatures is one ting, but do you do actual measurements to see what factor the ambient temperature has on the measured temperature of a phone battery? How about having the phone touch a 37 degrees centigrade heat bath on one side (in other words: a human body) and ambient air on the other? Before this paper, could you have made any reliable prediction on how big an influence ambient temperatures were on the sensors in the battery?
Knowing how much of that temperature is body heat, ambient heat and heat produced by the phone/battery requires analysing the data - for all we know the ambient temperature could have been completely insignificant compared to body heat and heat produced by the phone. Maybe you could model it and predict it, but even then the proof of the pudding is in the eating.
You and others here can complain that it's no surprise that thermometers measure temperature, but actually analyzing the data, discovering that ambient temperature is a significant factor, and figuring out the Pearson coefficient required to put it to use is a discovery, and certainly worth publishing about.