Most people will just be like "Oh well, Speed and Con are both good, so I'll just go with whatever I get" instead of "Well shit, I'm a rogue, I guess I HAVE to be heartless."
I think this is a good argument for removing the bonuses entirely. How do the bonuses make the traits any more interesting at all?
The point that people have been making is that they don't want to mix the roleplaying and the combat. They don't want to be making a choice while roleplaying that will affect their build in combat. You're essentially arguing the same thing -- you don't want to be prevented from making a choice when you feel the reward is not rogue-appropriate or whatever.
I don't believe that choices should be equally valuable, and I believe that the whole point of having stats is to enable min-maxing. However, this should allow for different choices to benefit different strategies or play styles. Choosing between speed and constitution should be an important choice.
So I think the best solution is to focus on providing roleplaying rewards for roleplaying decisions.