There was no need in the world the colour needed to change in the first place. Passports of countries in the EU can be whatever colour a country wishes. Here is a Croatian example, where they retained the original colour.

Changing the colour to Maroon was just another of the daft changes Margaret Thatcher imposed on us, brought in for some weird reason when she took the country into the EU without bothering to have a referendum, unlike Ireland,for example.