Why aren't there any commodores in Star Trek: The Next Generation and after?

Prompted by this question, "Does James Kirk have any named superiors in Star Trek: The Original Series?", and the accepted answer which lists several of Kirk's superiors. A lot of them have the rank commodore.

That caught me by surprise. In TNG and on, the Starfleet captains are seen answering to several admirals, but I can't recall a single commodore. In-universe and out, is there a reason the rank was largely (if not entirely) dropped?

Answer

As a matter of fact there is one (solitary) mention of a Starfleet commodore in TNG in a scene in TNG: Conspiracy, only viewable with freeze-frame.

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The Star Trek Encyclopedia makes a brief mention that the rank has fallen "into disuse" in the period between TOS and TNG.

commodore.

Title formerly given to high-ranking Starfleet officers such as those in charge of a starbase. The term commodore, used in the original Star Trek series, has fallen into disuse since Star Trek: The Next Generation.

Out of universe, the removal of this term seems to coincide with (and presumably relate to) the decision by the US Navy to largely cease using the term to describe flag officers.

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For the record, the rank also make a brief appearance in TNG: The Enemy when Geordi describes a Romulan as "commodore". It's not clear whether the Romulans have continued to use this rank.

LAFORGE: You really believe that stuff, don't you, Commodore?

BOCHRA: You may address me as Centurion Bochra.

_{^{TNG: The Enemy}}