[zarro]

Define "Realistically". Also define "desirability". You could make equally strong arguments both ways.

Example: If you are depressed you are more likely to focus on input data that is 'negative' and overlook the 'positive' data. For instance if your depressed, instead of focusing on the different ways people are trying to improve the conditions of existence, you could focus on "the shitty conditions in india/africa/china/etc.) You could say this is more "realistic".

Example: If you are optimistic on the other hand, you could say to yourself, I have no control over those variables that make the world 'shitty', let me try and focus on the variables that make the world 'positive' and see if I can affect them, so that the world as a whole can be more "positive". Some could say this is "unrealistic".

Which is more "desirable" I would argue the latter, but I hope the argument has shown that these are value judgements subjective to the individual.