What problems can unpruned trees cause?
Overgrown tree limbs will be to overcrowd other species of tree. Which isn’t aesthetically pleasing.
Blocking natural light to your home or garden. If you have other trees or plants in your garden an overgrown tree can block out the existential light needed.
Large limbs that become overgrown could be in danger of snapping during storms or windy weather. Causing costly damage to its surroundings.