Why we use cross cable for same device? and stright cable for diffrent devices and why?

it is beacause the terminations for the receive and transmit points are the same at both ends so the receive termination is crossed over to the transmit termination at the other end and vice versa. 

Howerver, devices are now built with intelligence to automatically detect and adjust it's transmit and receive termintaion which allows one to use stright through cable for same device .

Its also because theres a connection that are not compatible in cross connection thats why they find other way . They try another connection which the straight connection.. then suddenly they found out that the straight connection cable is better than the cross through