Um. Yes I DO worry about heat in the above mentioned items. Even AAA says don't warm your car up too long on a winter day or you hurt the engine. And yes if an item is constantly working to the extreme range of heat tolerances without much headroom to allow for a high ambient temperature, that means the engineer did a poor job constructing the machine.
Intel's i7 chips have a threshold of 100° C. They have been reported to be running hot at around 95 to 100°. That is a problem and they have been getting crap for it.
Honestly your responses are not helpful. If you don't know specifics of what the CPU temps of the i5 and i7 are in the Mac Mini, please refrain.