Not sure why the confusion (by anyone). The article clearly states why they've reintroduced the 60 - customer demand/enough people have been asking for it.
Maybe it's that people forget that demand for any product isn't static that's got people confused? The 60 was popular enough that Tesla made them for a couple years. Then Tesla went to the 70 and then the 75. Even though Tesla kept the pricing under control, it still increased.
During all this time with the bigger batteries, more and more Teslas have hit the road. Model 3 has been shown. Point being, more and more people have become aware of Tesla, test driven one etc... every single day. Clearly a big enough group of those people want a slightly more downstream Model S. Voila, 60 returns (but with the ability to be upgraded to a 75, if/when someone changes their mind OR the car is sold to someone else used and that person wants more capacity) - which brings me to the next point - more Model S's on the road, more (lesser expensive) Model S's available for purchase used, more Model S's are bought, more Model S's on the road, more (lesser expensive) Model S's available for purchase used...
It's all good peeps.