Only for light weapons. Improved Weapon Finesse allow non-light finessable weapons to also use Dex to damage (although that list is short: Rapier only, I think), and most importantly, Dex to damage with bows is a major game changer for future builds and was only accessible via 18 AP on the Elf racial tree.
Also, it is accessible from level 2, while Tempest get this as the third core (level 6). So, lower gating for splash options.