>Legend of Korra stuff on the article picture
Allow me to sit here and watch the shitstorm that's about to ensue.
Sorry, regardless of the deep psychological issues I'm sure this helps with, fat weeaboos dressed up as kawaii desu anime characters are still funny.
What we wear always stands at the intersection between what we want to wear, what we want to be seen wearing, and what is socially acceptable to wear. Not to wax too philosophical, but in some ways we are always wearing a costume based on these criteria, whether you're going to work, a park, a mall, or a restaurant. When one of the above criteria changes, we tend to change our dress. Wearing Yoko cosplay even for a day in the "outer world" will be seen as rather strange, but in at an anime convention it's not just socially acceptable, but it could be lauded.
The displacement idea is interesting in this framework, but I think it's less about wanting to escape "reality" and more about using the opportunity of an anime convention to have fun and express love for a fandom in a mostly supportive environment. It's a practical thing, the same reason someone wears a shirt/tie/dress/etc. to a professional environment.