@OP

Fundamentally, customization is never additive. It is purely restrictive.

Its only benefits, therefore, occur when the concepts cohesive to a class's identity outnumber the concepts mutually cohesive in gameplay. In this sense, a job of "over-abundant" prospects can be pared down into sensible spins on the same theme, allowing for greater breadth of player attraction to the class than could be achieved by selecting only the best, unrestricted translation of theme to gameplay. This benefit is rarely present except in games with excessive bloat or particularly low confidence in their players' skill levels and a low desired skill requirement from said players.

You can have tremendous depth and breadth without spending time in menus (and just as likely, on forums or guides to dictate your choices to you). Take Enochian for example. Imagine if it could have any of three mechanical bonuses, for Ice, Lightning, or Fire. Like gameplay-replacements such as customization menus, gameplay itself tends towards rigid fight-by-fight min-maxing, but it can still provide distinct gameplay strategies -- ideally distinct also in playflow -- that are within a hair's breadth of each other in output, allowing for multiple ways to play at least as surely as any talent system. Perhaps a certain mechanic receives more advantage from the draw-in or repulsion side-benefits of Thundercaller (Lightning-Enochian), and so it sees frequent use starting just before that mechanic, but unless prepared for appropriately off of either an earlier use of the same or a well-timed build off of Flamespeaker (Fire-Enochian) or Breath of Winter (Ice-Enochian), it stands as a compromise. Ideal gameplay allows for constant improvement, revision, and experimentation between macrorotational elements that feel distinct from each other as to add breadth to the class's experience without forcing every aspect upon the player (who may rather avoid certain mechanics' use, especially while still learning). Learning one's job should be a less an improvement to sustained or theoretical damage, which should allow for multiple ways to "play" the job, and much more a fight-by-fight nuanced mastery by which you can adapt to any situation (breadth of toolkit).