Two reasons to take the feat over a Dexterity boost:
- You frequently use double throwing weapons and want to be able to "reload" both hands in one turn, or frequently start ranged and then close in for melee.
RAW does not allow for drawing two weapons in one turn (with a single "free object interaction"). Generally, this is only relevant for one turn, but it is an early turn which makes it important because (a) some combats are short and (b) because downing enemies at the beginning improves your side's advantage in the action economy.
- You are bothered, from an RP perspective, that the only extensively developed real world forms of dual wielding (rapier with dagger fighting and the much rarer rapier with rapier fighting) can't be replicated in game without this feat.
This is something you may be able to work out with your DM without the feat since rapier(1d8) and dagger(1d4) is the damage equivalent of double short swords(2d6), and it really doesn't make sense that two hands can not draw two weapons when two-weapon fighting is generally available, and is also a fighting style for Fighters and Rangers.