I know that over time individuals have requested a dark theme for what ever reason. Let me put a reason in your realm of reality. VISION IMPAIRED INDIVIDUALS! You are eliminating a huge customer base of the elderly and vision impaired. I have Retinitus Pigmentosa. I am blind in the left eye and have 30% vision in the right eye. The #1 issue for me is the brightness of the backgrounds compared to the letters. I use black background with white or lime green lettering on everything. I have reached a point to where CCleaner's white background is like a flood light shining directly into my eyes. Pretty much useless to me now! I guarantee you that I am not the only one with these issues. Why do you think almost all programs, operating systems, etc. have implemented High Contrast settings which I use on everything. CCleaner is not High Contrast compatible!
To give you an example of many individuals with these issues, I use a 55” tv for a monitor and in the near future will need to go even larger. I am typing this and each letter and cursor on the screen is .75 inches tall with dark background so that I can actual see with my glasses on. I also am typing this in MSWord that is full screen width and will copy and paste to your support. DARK BACKGROUND PLEASE! It would help many tremendously!