Pruning and reshaping trees is very common. Many low spreading trees like Mango and Figs are often reduced in height, but care should be taken as limbs previously shaped for light can sunburn causing irreparable damage.
Lopping the tops off tall upright trees like Eucalyptus is wrong on every level. It is often done from the misplaced belief that the tree is safer being shorter however, the epicormic regrowth that results is poorly attached making it more susceptible to hazard than the original.
Pruning the top off your Mango tree does not mean that new branches are going to miraculously sprout at lower levels making the fruit more accessible.
Pruning of fruit trees
Thinning out of fine twiggy growth of citrus cutting internal branches to allow light and air movement.
After fruiting, light pruning of Mangoes and other fruit trees to promote future flowering and fruiting.