here is a proof that you can get kinda high herbalism:
The World of Warcraft Armory
Working as Intended therefore not an exploit.
Seems to be nice!
In 3.0 gathering professions got a level requirement to train (just like crafting professions do), if you leveled up mining/skinning/herbalism pre 3.0 you'll get the highlevel passive buffs, but for all new twinks you can't get more than 150 in ANY profession.
If you don't care about engineering, I suggest Herbalism as second main profession, Lifeblood rank 1 does 300 healing over 5 seconds.
Need level 5 to start any profession. =]
For Skinning, no requirement needed to increase the level cap.
This is not an exploit, Work as intended.
It just the idea = kickass. Keep it up.