Here's a trick from the old playbook that can help with the too dark issue.
In client settings under the renderer section there is a variable called GammaRamp. Its default is 1 and it's not always listed (and is then assumed to be 1) so you might need to dropdown a line and add it.
Path is C:\Users\<UserName>\AppData\Local\SWTOR\swtor\settings and file is client_settings. Double click to open, edit, then save.
I'd start with GammaRamp = 1.1
You can adjust it up or down from there. On a dozen computer/monitor combos over the years, it usually is between 1.1 and 1.3 for me. Think of it as having a Gamma slider that goes to 110 or 130%.
I had this set to 1.15 on my current system, then when the last patch came out, it rewrote my client_settings file and changed it back to 1. I noticed as soon as I logged in, and changed it back to 1.15. The game would be too dark for me to play without doing that, I would have quit years ago.
Hope this helps someone?