Question

why do organisms have to be so organised

Answer 1

Is this a joke or did you mean "classified?"

If you meant classified, it allows scientists on a world wide basis to talk to each other and know what species have been found. It organizes all the species so they are easy to find depending on their characteristics. If they weren't organized, it would take forever to find out what you are looking at.

Answer 2

well I mean organisms are organized into different phyla and kingdoms but also the way they are structured on the inside is very organized like the cells that make up the tissues and the tissues that make up the organs the organs make up the systems and the systems make up the organism if that what you mean