LPS-48693 added a 'Cacheable' check-box for Web Content templates. The presence of a 'Cacheable' column on the DDMTemplate table for Application Display Templates indicates that there should be such a check-box for whether or not the template is chacheable for Application Display templates as well. However, no such checkbox exists.
Furthermore, implementing caching for Application Display templates in the same manner as Web Content templates would cause them to lose their dynamic quality. A good middle-ground would be to add a 'Timed cacheable' option for Application Display templates that would allow them to be cached for a set period of time, which would boost performance for customers utilizing them, but would also allow them to maintain a level of their dynamic quality.