Frankly if they knew they were going to be PSO2 Meseta making and releasing New Genesis, why did they bother porting the soon-to-be-obsolete variation to NA if not to snag some money from the early adopters?

They will be implementing the graphics engine update to the first PSO2 also so that it will continue to exist next to NGS instead of only be abandoned.

They likely figured that people would want to be able to go through the first PSO2 how JP players did so , when NGS comes, they could experience with exactly the exact same circumstance that JP gamers had/have. They have also expressed that they want JP and NA to eventually be in sync, so this gives a route so that NA players can reach at the same point as JP players in an more-accelerated manner.

You can look at any F2P match cynically in that sense -- that the sole reason to launch any F2P match (or game, really) would be to at least break-even or profit. But if they had just launched NGS without bringing through the original PSO2 in any way, there would be a lot of content NA players could be missing out on, which includes items you can buy in buy Phantasy Star Online 2 Meseta and take over to NGS. (Which is why even using Tweaker and playing on the JP servers would not be the same, as you couldn't take any of that over to NA servers.) Plus, since they chose original PSO2 will stand alongside NGS, they were going to need to port both over anyway, better to do it in stages.