Why are some lands that show a specific, named place (Rix Maadi Dungeon Palace, Tree of Tales, Valakut the Molten Pinnacle) nonlegendary while others (Minamo, Nykthos, Eye of Ugin) are legendary?

We stopped doing Legendary lands (mostly) for a while because we didn’t like the gameplay, but the recent change to the Legendary rule allows us to make them again.

Kamigawa may have been a legitimate design flaw, but I can tell you that as a setting, it was brilliant, and it's one of the most popular blocks in EDH (not just because of having many Legendaries, but in general). The only issue was the mechanics were weak and slow, and the Kami were weird. But Minamo Academy, Oboro and the Moonfolk etc. were all successes. Everyone loves Tamiyo.

I believe players love elements of Kamigawa block although I believe the huge numbers of legendary creatures is the primary cause for the Commander love. We tested the creative as well as the cards and the world (once again, not just the cards) didn’t test well. It didn’t quite jell with a majority of the players.  The reason I think there are people who are huge fans of Kamigawa is that there are elements that are very cool. The source material has tons of fans so it seems to reason that players would like those elements they see reflected in the game. Tamiyo, by the way, has a very split reaction. She tends to be polarizing. Those that like her really like her but those that don’t really don’t. Now I think Magic should have polarizing things so I’m a huge fan of Tamiyo. Worlds, though, are not the things that are supposed to be polarizing. We want as many players as possible to love our worlds. As you saw in Planechase 2, we understand their are fans of parts of Kamigawa and we will try where appropriate to do some fan service for those players. I’m just trying to be honest with all of you and say that I don’t see a Return to Kamigawa being the best way for us to capture many of those things that players loved from the original block.