The trouble is that some players, myself included, enjoy playing without human contact. Just going off into the wilderness and becoming a hermit. Your suggestion would mean raising herblore becoming impossible.
Of course, so long as those like me could still grind herblore the old way, I would have no problems with your idea - it's a pain in the arse to grind and anything that eases this without unbalancing the game is very welcome.
I do think grinding herblore needs tweaking. For starters, it should do every herb in the inventory at once, so fewer keystrokes and fewer people taking Sami to court for giving them RSI. I also don't see it as simply pondering the herb, you'd be smelling it, rubbing it on a sensitive bit of skin, kissing it, even putting it in your mouth (stop sniggering at the back there!). I think herblore should raise a lot faster; but using it should take longer than a minute or two and use up a portion of the herb, much as how bait bait is used up as you fish with it.