Spiritually, inside may have connotations of protectiveness and of a degree of introversion. Being inside suggests the need for some spiritual awareness, of being permitted to enter an inner sanctum.
Psychological / emotional perspective: Being shut in suggests that we are emotionally restricted and may feel we cannot express ourselves properly. Going into a building in dreams, for example, suggests we should explore the structure of our lives.
Material aspects: In dreams, exploring the inside of something as opposed to the outside suggests that we need to explore motivation in some way. Being stuck inside suggests we are aware of circumstances around us that are preventing us from moving forward. This may, of course, be due to our own attitudes.