The Virtual Boy was an idea ahead of its time, and Nintendo was wrong to attempt it with mid-1990s consumer technology. The Virtual Boy's existence was therefore a mistake. You can say it's a fun little failure, but you can't excuse Nintendo pushing it to the market.
What's the advantage to cartridges beyond durability and the lack of loading times, neither of which improves actual game design?There were and will always been some clear advantages to carts.