The lack of GO's and most other commemoratives is also partly down to the Japanese takeover of GPI and the replacement of most of the old salesmen, including for Nevada.
GPI salesmen used to earn 80% of their money from commission on sales. They were incentivised to suggest to casinos that they made commemoratives, and demonstrated the value to the casino by referencing what Gene had done etc.
Modern day Japanese owned corps don't work the same way. Good salaries (and typically long hours) but minimal commission.

Btw, that's not my speculation, it's based on conversations with several now ex-employees over breakfast and lunch back on Superbowl week.

Also, changes in pricing structure, like discounts for small inlays, and horrendous artwork charges for anything not really simple (particularly for the smaller casinos) has resulted in the majority of the last few years new house racks being pretty bland.
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