No Mac mini design ever had heat issues. I'm having several models, including the original one from 2004 and the 2011 model. Every single one runs cool. .
The 2011 and 21012 are NOT running cool, 98 C under load is not cool. Perhaps if you only browse the web then it is running "cool" but to me cool is below 65 C at maximum load.
And do not start spouting that the Apple engineers know what they are doing - just check out what the maximum temperature is for the CMOS battery or for the memory or SSD for that matter and then you'll see that they are not designed to be used at 98C.