It's because people used to (still do?) those "power ball" type things in game, basically. It's about player-run gambling games in game, not things like gambling on upgrades or items.
Familiar healing probably should be disabled, but they haven't disabled it on any other bosses, plus other than releasing new familiars, they haven't really updated the system or anything in quite a while.
It seems the point of certain items of Taiwanese origin (Breath of Divinity, Frenzy Totem, Lucid Earrings, plus stuff we don't have, like Auto-Buff Earrings, the ring that pulls mobs to you, the effect on Orchid's Badge), are to bypass normal in-game mechanics (politeness aside, what I really mean is that they're stupidly broken), so, while I don't exactly like it myself, it is what they're for and I don't see them changing that.
The gloves have MaxHP, not MaxMP, and Kanna has a skill that increases their magic attack by the amount of HP they have. Not considering any % HP boosts you may have, tne gloves are already worth almost 3 magic attack on their own.
I can't really say why 24 INT would only translate to a 44 att increase, or if that's even an error or not without knowing more about your overall stats.
what about the player that already spend thousands on bonus potentials. This would be a turn-off for them.
What about the players that spent thousands on miracle cubes, premium miracle cubes, super miracle cubes, revolutionary miracle cubes, enlightening miracle cubes, memorial miracle cubes, platinum miracle cubes, and all the other now sub-par and more costly cubes compared to the red and black cubes we have now?