Yes the ban on plastics is justified as

a. Plastic is non-biodegradable waste.

b. Burning of plastics release toxic gases which cause pollution and health hazards.

c. If not discarded properly it chocks drainage system causing problems.

d. Animals eat plastics which cause death.

e. It is hazardous to marine and aquatic life too.

f. They cause solid waste problems.

People are using paper bags instead of plastic bags due to this ban and thus reducing the use of plastics. They are also taking proper care of plastic disposal thus wastes caused by plastics is getting reduced.