Fair, though getting a PLD to 60 in the span where you're still a sprout is really easy now with all the enhanced EXP and not needing to level CNJ to 15 as well.
Putting that aside along with the bot problem, since that is a problem and always will be, I don't see how: "New player uses jump potion" + "Jumped PLD doesn't use Shield Oath and doesn't respond" = "Jump potions are bad and should be removed"
To me that seems more like a player issue, not specifically the item issue. There are ways that could be remedied by forcing players who jump to finish some starter training before being able to play in dungeon content (annoying for people jumping alts, but small price to pay), but once again that's a player issue, not a item issue in my opinion.