Here's a logic question for the community.
If you believe that Producer/Director Yoshida will listen to testing feedback and make changes accordingly,
- AND -
That some changes and adjustments will definitely be required ...
- THEN -
Would it not be extra development work to build everything all at once to work with the original system mechanics, then have to re-build everything again once you get feedback to alter something in that system??
Let's say, for example, that global cooldowns is just a big flop. Or that auto-attack is just too powerful, or that the HQ synthesis rate is excessively high.
Isn't easier to test the fixes to these possible global system problems on a small scale with a small sample, see if it works, then build the remainder to the new working model ... instead having to build, then rebuild everything, perhaps repeatedly??
Once you have the global world-defining systems nailed down, then you can introduce and test specific case scenario's and fix them individually. Bard Arrow-Burn parties are clearing dungeons in a quarter of the expected time? Player feedback is asking for Paladin's Cover ability to be an AOE semi-circle behind them? Those types of issues are better nailed down after the primary systems are tested and finalized.
Be patient. It's a process. Let the process run. After bringing FFXIV from 1.0 to 1.23, do you still not trust that Naoki Yoshida knows how to run a development team and get results??
tl;dr -
It's faster to test and re-test fixes on 3 classes (or one zone) multiple times and then move the fixes out to the remaining classes ONCE, than it is to test and re-test fixes on all the classes multiple times.