It's also been mentioned that it would be useful for the rain to give the grass growth a bump in speed.
So say that normally, grass growth would be +5. On a rainy day, it would get bumped up to +10, making the grass grow twice as fast as it normally would.
Personally, I like the tracks, it was a great idea and works well if you use the function properly. But my gripe with it is like above, the grass grows back way too slow. If you can leave your game for three days and come back with weeds growing in your town, why can't the grass grow quicker?
But like n00srac said, if we're aware of it beforehand we'll know to be cautious.
Also to help you with your fossil problem, I would make my paths intersect. So instead of having one or two paths that went from A to B, I had it so all of my paths connected in a sort of deformed grid to cover areas where there was nothing but open space.