That in itself makes the Type 005 a liability, if your using more expensive units to shield your 20+ level unit from ranged attacks, your risking a far more cost-efficient unit to protect a lack-luster one.
It is not at all a liability to use a powerful unit to block attacks if that unit can reliably avoid all damage. Then the units he is protecting become a great offensive team. Thus the long used strategy of many Azur Alliance players to use Alastor to tank though he is usually the most expensive character in their force.
Now, if your spending the time to upgrade the Type 005, it can certainly get 5/6 base attack/damage, but your spending more points per Type 005 and using up an advantage card slot.
An advantage card slot is no big deal for Black Sun teams running a lot of undead. The teams here locally struggle to find beneficial advantage cards to play with their points.
Anyways I'm not a fan of the Type-005, but I do think they have potential when they get a few key buffs.