I agree with SE on this topic... Besides the monsters mentioned in the OP have very little to offer us with regards to the current state of the game. I feel you guys are just looking at monsters and judging them based off how menacing/bad-ass they look without actually considering how useful they would be.
I can find more useful monsters that we can already charm or pets we used to have as jugs before the level cap:
Lizards
Notable Abilities
Infrasonics: Conal Evasion Down -25%, Duration 3:00
Giant Bats
Notable Abilities
Ultrasonics: AOE Evasion Down -25, Duration ~3:00
Subsonics: AOE Defense Down -25%, Duration ~90 seconds
Slugs
Notable Abilities
Corrosive Ooze: Attack Down-33%, Defense Down-33%, duration 70~90 seconds
Purulent Ooze: Bio, Max HP-10%
Beetles
Notable Abilities
Hi-Freq Field: Conal Evasion Down -25%, Duration ~3:00(Overwrites itself)
Oddly enough, PanzerGalahad (HQ Beetle Lv 63) has this ability but he caps at 75.
Dhalmel
Notable Abilities
Sonic Wave: Conal Defense Down-50%, Duration 3:00~3:30
Berserk: Attack+50%,Defense-50%, Duration 3:00
Healing Breeze: AOE HP recovery similar to wild carrot.Dhalmels in Abyssea-Altepa recover 750~1300 HP.
Dhalmel jug alone would be absurdly powerful. I can't see SE adding such a jug unless it was tied to R/E/M or some other Hard to achieve item and I honestly wouldn't mind at all.