Vss and Vdd pins' position on microcontrollers
As you say, it is a complete non-issue for high-volume manufacturing, which is where the vast bulk of such chips goes &mdash; and those are the customers that the chip makers pay attention to. Hobbyists don't buy nearly enough chips for them to even notice.

But yes, there are real advantages to this arrangement, both on the chip and on the board. Power and ground are distributed on the chip in metal layers on top of the silicon, and these connections interfere the least with signal connections if they run parallel to each other to the greatest extent possible, and this includes the external contacts.

On the PCB, you get the best performance out of the decoupling capacitors if their connections are as short as possible, and putting the pins on the chip next to each other makes this much easier. It also helps avoid congestion with signal connections here, as well.