If you didn't know it had tile tweaks, and its been tweaked extensively, how do you know that tweaks we'd make now couldn't be a significant improvement over default?
The fact is, that the original values were implemented with comparitively little playtesting. Three years have elapsed since.
Without actually playtesting different values, its very difficult to say whether something is good or bad, although there are a couple of constants...
Production is important early. Starting positions should tend to give roughly equivalent resources. Forests shouldn't be a penalty.
Changing the production value of a beach to make it a moderately negative terrain isn't a significantly unbalancing situation, since there is only one kind of beach... and every costal city is in the same boat.
Given that values are merely relative, decreasing the values from ideal to less than ideal, has relatively little ultimate effect. The tile improvement effects have always been more significant in CTP2, anyway.
Its about PW in CTP2, not whales or cows.