Why Is Brightness Control So Dim?

I have a Logitech Illuminated Keyboard on my desktop computer that has four brightness settings for the backlighting. When I shut down the computer and restart it, it remembers where it was set.

On my Dell XPS laptop, I can set the screen brightness for both battery and AC power conditions and it remembers which is which without fail.

In contrast to these Windows machines, the MBP is absolutely random in how it behaves. It will blaze at full battery-gobbling power while unplugged and then run at half-brightness while plugged in. I just noticed that the keyboard backlight was totally off and screen was at 1/2 while plugged in. The room light compensation is disabled, so I don't get what the problem is.

For a computer that's supposed to be the cat's meow for "professional" graphics users who rely on precise display output, the fact that you can't trust that the display is running at proper level is just ridiculous. It's bad enough that this panel requires more profile compensation than any other display I have, but if I was to do any serious photo editing, I'd be at risk of having it all screwed up. I once did several hours work on the XPS with the color profile not applied and it sucks.