This has been known for a long time, even during the beta. I'm not holding my breath for Larian to change this anytime soon.
I don't actually think the "extra" penalty on hard is that much of a problem. My GC character doesn't really die any more than my non-GC characters, and it's kind of sickening how many AP she has. It is, however, unexpected from the way the tooltips are worded and that IS a problem. Some extra words in there like "this penalty stacks additively with difficulty modifiers" would be nice.
