I love uliwooly answer but it's quite platonic haha.
Some themes are not available in some countries due the content. Some contents may be inappropriate for a specific race or religion, some contents won't apply like Maison Kitsune which I think no one knows except Americans (not just USA) and Europeans and, at the end, some themes are about movies or events that are not going to be released in India or need to be yet announced.
Same apply for some apps, and it's not just Sony policy but it's global.