In game design 'utility' can be really hard to codify, because it comes in two flavors: Tangible (Ex: Trick attack, dance partner, regens, leylines), and Intangible (Ex: En Avant).

If utility is something that is adding to a numerical value that your constantly comparing, it is easy to design but can often feel either invisible (Ex: Bard songs), helpful (regens when they won't ever be a difference maker in even getting the healer one more cast), or overwhelming (old trick attack or piercing/slashing debuffs for example). Its also hard to make even really strong ones feel good or to make them noticeable for your teammates. A few feel REALLY good (Leylines) because they both are a meaningful DPS increase AND are visible in how they are helping you (It isn't an accident many of the 'fun' utility is a speed increase, because casting more is very visible), but overall even when these are good they lack any real 'highpoint' compared to a big attack with a flashy animation.

Intangible utility is easier to make feel impactful to some degree, and as long as their use cases come up remotely often (ex: Aetherial Manipulation and Between the Lines are very frequently useful to maintain uptime), but they can be much harder to keep relevant (Ex: DPS Esunas, heavies, stuns) because they can break encounters, and its harder to overall design them because by their nature they are introducing entirely new mechanics to the fight. Most of the ones that 'work' in XIV are movement, and tank damage reduction effects, though "rez-mage" gets a special mention. XIV used to have more of these, but most were considered bad (ex: Ewer cards) or frustrating to use (manashift) and the game pushed away from these.

XIV tries very hard to push away from 'meta' comps and so complicated ability interactions between players are de-emphasized. In some ways this is good (Its nice to not be locked into DRG+BRD super hard) in other ways it limits the design space for utility a bit. Visible, impactful, offensive utility can have serious implication for other kits. Despite the fact most 'fun' self buffs we see are either a total transformation of abilities or attack speed increases, there is a reason attack speed increases went away. Likewise, defensive/healing utility is rough because the very concept of healing is strange in game design overall, because all healing that doesn't directly save the target is 'wasted,' so unless healing can get so demanding the healers alone can't cover it, or unless your heal effect is so powerful it saves a healer GCD, healing or defensive buffs are 'worthless.' And intangible benefits require fight design complicated enough for your intangiable utility to meaningfully alter it, which is hard without creating fights that 'require' certain types of party members, so we tend to only see intangible utility when they are very 'internal' to the character and accomplish something that naturally fits into how the job plays anyway (like BLM).