What is even more puzzling is why so many people are thinking and writing things like that in a complete disregard of the existing evidence.
Can you please clarify how exactly creation of a multinational empire where trade flourished and a person could securely and reasonably comfortably travel from, say, Volga, to China would be a manifestation of a "destructive mindset"?
Did not try to read his books on Genghis but it is a literature with the same dangers as confusing Henry V from Shakespeare's play with a real person.
FYI, burning down a city was a common practice not only during the ancient and medieval times but in quite modern times as well. As for "killing all", people tend not to pay attention to the fact that quite often this complete extermination of a population was quite often reported either by someone who lived in that city (which means that "all" is an exaggeration) or by a person who lived in a different time and place (and often did not have a clue). And, another intriguing phenomena, in most cases almost immediately after all that complete destruction and annihilation we are seeing mentioning of that destroyed city not as a big functioning local center with the population of all ages and occupations.
Then, of course, comes another set of questions (what's below is far from a complete list):
1. How come that with the Mongols presumably killing everybody in the Northern China (which is well before Khunilay's time), the Chinese had been defecting to their side not just on individual basis but by the whole provinces and armies. By 1237 there were more than 4,000 Chinese officials handling administration of the conquered provinces and Mukhali's army had significant number of the Chinese contingents (not to mention that the Chinese engineers had been incorporated into the armies fighting elsewhere). BTW, when Kublai got into the picture, the Northern China was not exactly a desert littered by the corpses and smoking ruins which means that the previous Khans were not just a bunch of the murderous maniacs.
2. How come that after (presumably) a complete destruction of the Central Asia with the whole population being either killed or transported to Mongolia most of the big cities were still there and functioning and you could find numerous locals in various positions within imperial administration (in and outside the CA)?
3. How come that after (presumably) a complete destruction of the Central Russia with a thorough annihilation of the ruling families, not only most of the (burned to the ground with everybody inside being killed) cities were functioning almost immediately after their destruction but we can also see an impressive number of the local princes surprisingly alive and competing with each other at Khan's court for the right to rule these "ruins"? So-called "Golden Horde" (Vernadsky proved that the name is anachronistic and invented by the later Western travelers; a peripheral ulus could not be "Gold" - this color being reserved for the Great Khan) was by all accounts very rich and the riches had been coming from ...er... burned to the ground territory where all population had been massacred (

).
4. How come that immediately after conquest of the Eastern Europe (from Ural to Volga - Don steppes) the Mongols immediately started creation of a new state (and a nation in which they were a minority) with its own cities which flourished all the time until Timur destroyed them? Is this an indication of a "destructive mind"?
The Mongols had been destroying the resisting places and people. Those that submitted upon request just paid tribute. The patter existed since the time of Genghis and Kublai did not invent it. It is just that he conducted conquest of the Southern China from a position that was much stronger than one of Genghis when he started his conquests.