Just for that I gave you an "unearned" point for the submission you referenced ^_^.
Seriously, if you post something that provokes really good (useful, whatever) comments, you've done something good for the community and a positive reward for that is hardly unearned.
I agree in principle, I just feel that the reward is totally out of proportion. Anyone, including the author, could have submitted exactly the same link for a huge reward. the 'A new approach to China' post by Google did the same thing for someone else, catapulting them from ~50 points to well over 1000.
Hmmm, I now feel we're at a "What's your price?" level of agreement (the old "Would you sleep with me for a million pounds?" joke), in that I agree 1,000+ points for forwarding an item is beyond ridiculous (and for something like that a "please drop my karma" option would be worth it ... although I'd assume 1,000 point boosts are very rare).
Your case of a bit over 50? Out of proportion, very possibly (I don't pay close attention to this level of detail), but maybe not "totally".
Then there's the "this rewards one for other worthwhile items forwarded that got lost in the crowd" theory. For those driven, at least in part, by a desire for more karma, this encourages them to continue to forward worthwhile things. If it encourages them while not discouraging you from continuing to forward items....
Seriously, if you post something that provokes really good (useful, whatever) comments, you've done something good for the community and a positive reward for that is hardly unearned.