At first I was like you, OP. But after playing gatherer and almost spending 99 tickets on gathering leve's I can tell you that the GP regen is just right imo.
You can use the potion if you want t oget the GP back, but I save those for personal gathering needs rather than using it on gathering leve, and like Orophin said, I did lv40-45 guild leve and use 2x250GP skill ups on 2 nodes and stick with the 100GP skills on the other ones and still have no problem getting the 25% exp bonus reward.