With multi grade (0w30), the 30 fulfils all the high temperature requirements for Pakistan.
Brother, with advancement in technology, the clearances between the moving parts in modern vehicle engines have come down with manufacturers recommending thinner oils accordingly.
You should know that about 70% wear and tear of an engine takes place from cold engine start up till it achieves normal operating temperature. Hence, this initial period of engine warm up is more critical for which the manufacturer has recommended thinner oils.
One can slightly deviate from the recommendations but the manufacturer them selves set the range. Like 0w20 is the recommendation but 5w20, 0w30 and 5w30 could also be used.
Also, with more mileage on the odometer (above 100K), one can go for slightly thicker oils. For 1Kr-fe engine, 40 is too thick with only 10500 miles on the odometer.