The billion units was primarily to help in marketing. It gives us a nice round number to start with for supply (vs. 1,783,034) and it creates the perception of value (eg, feels better to tip 100PTS than 0.1PTS). Perception drives reality.
I agree this is an unnecessary and distracting change. Changing the number of units again feels like a new project, rather than an upgrade. Maybe a 1.8 mil hardcap, with the the last 40,000 set aside for transaction subsidies.
I think the community and exchanges are fairly accustomed to this by now. There is broad enough support that I don't think the scaling will be a problem, especially now that the PoW chain has almost ground to a complete halt.
I've already pledged that I will not support any pre-mine, dilution, or change to the snapshot allocation, so I think inflating for subsidies is a non-starter. One thing I will say is that with most things there are a million wrong ways to do it and a handful of right ways. For all the things that could be done better, I think the plan I've outlined reaches common ground among PTS holders on the most important points.