There are multiple reason to implement this:

• Possibility to experiment new primary/secondary combinations without losing you favourite one;

• Quick switch between your custom themes;

• Option to have your themes (official or custom) switch automaticaly after the selected number of minutes or in different hour of the day;

• Creation of a community that exchange their custom themes (accessible with the forum or with the opera addons);

• Possibility to save custom themes not only locally but also on your opera account;

These new function not only will bring new features in our favourite browser but also will result in a creation of new opera accounts (investors, i'm looking at you) since there will be a new functionality to them and will create a community of themes sharer.

Thank you for your attention, hope to see this functionality in the new updates