Carbuncle simply became a landing point for elemental summons not a particularly interesting design, The AIs of old EGIs were admittedly pretty bad but the devs could make the carbuncle more useful to the summoner than a simple statue that does nothing,
for example by removing the current etherflow system, the carbuncle could start the fight with 3 primal ether which allow to cast special ogcd spells of the carbuncle and even during summon time(don't disappear anymore during summon),
for example a single-target spell Poison Nails instant and ranged poison damage that does not inflict a dot(cost 1 ether), and aoe spell meteorite, inflict aoe damage (cost 1 ether),
and a personal support spell Carbuncle's Favor, which causes the summoner to gain 15% personal damage during 15s, with a 120s cooldown and give 2 stacks of reinforced ruins with no time limit. (cost 1 ether).
When 3 ether primals are consumed, the summoner is able to command carbuncle to cast Holy mist, a powerful attack,
the carbuncle accumulates ether on its own during battle and will fully recharge the 3 primals ether after 45s.
It's quite similar to the old system that was in Haevensward yes without Dreadwyrm Trance, but the etherflow with energy drain/siphon system feels actually wierd and obsolete.
