i once heard a shiur listing all the mekoros that explain the shemira that tzitzis give a person. i remember the maggid shiur almost getting teary when he tried to convey how hard it should be to take them off, even for a good reason. imagine taking off bady armour in a battlefield to relieve yourself. yes, its a good reason and neccessary, but still understood why its a bidieved. so too should be taking off tzitzis.
