People often want to think that they have been Elizabeth I or Cleopatra or similar in a past life but the reality is that most people will have relatively mundane past lives! There are two ways (or probably more) of looking at the concept of past lives.
Firstly it can be an actual memory of a life that has been lived before. Secondly it can be connecting with the group consciousness and linking into information that is relevant for you at the time. Personally I do not consider that there is any particular issue with this – simply go with whichever description feels to sit best with you. After all we cannot categorically prove either thought and they may even both be correct we simply do not have the knowledge to explain the phenomenon at the moment.
Past life regression must not be treated lightly as it can open up issues that need to be addressed. So if used indiscriminately you may create issues. I use this therapy when it has been established that there is a past life issue that is playing out in your current life and that needs to be addressed. In this way you are dealing with the aspects that are most relevant to you at present.