~/.bash_profile and /etc/profile are only sourced by a BASH login shell. However, some variables such as PS1 should be set for all interactive shells since they are reset by default in new shells. Therefore, I recommend moving the setting of PS1 (and any other variables that may need changing based on the shell) to a /etc/bashrc file and have it sourced by /etc/skel/.bashrc so it runs by default. It may also be a good idea to source it in /etc/profile so current systems do not lose their PS1 with this change.
*** This bug has been marked as a duplicate of 26952 ***