It got carried over because the original concept for the battle system was gonna be an extension of the revamped system they did at the end of 1.23. where you actually had to build TP in order to do ya powerful combos which would have made combat a lot more tactical and less button spammy. In a sense of do you do your combo when you get to 1000TP or keep building to 3,000TP for a bigger burst of your combos later kinda sense...
https://media.wired.com/photos/59327...s/ffxiv_20.jpg
Skills in 1.23 felt alot more powerfull and had more weight because of this. where with the current system nothing carries any weight or feels like it packs a punch. it's just spam buttons to keep up some flashy lights and sparkles on your autoattacks. nothing feel special or powerful.
to this day i wish they'd go back to that system. was so much better and felt so much more powerfull when you did combos