Unfortunately, some large umbrella pines are removed for safety issues.  For example, a stretch of gorgeous umbrella pines along the lungarno in Florence was removed because some of them fell after a large storm and others were deemed unstable.  We have had a few removed from our small Tuscan town’s park because a large one fell during the day, almost harming a family having a picnic.  They’re beautiful, and provide wonderful shade, but some of the larger, unstable ones must be removed.  There is also talk of some Italian cities removing them because of their ties to fascism (many umbrella pines were planted in cities under Mussolini’s direction).  But, most are simply removed because they are safety hazards.