Coming from a Time interview with producer and Metroid series co-creator Yoshio Sakamoto...
On the inspiration behind Chozo design
"I think the Chozo artifacts and some of the other objects that appear through the franchise, probably some of that is inspired by the Egyptian cultures as other ancient civilizations. It's really just a great creative development, incorporating different civilizations and what this whole Chozo race would have been like, both culturally and aesthetically."
On bringing Metroid Samus Returns to 3DS with MecurySteam's help
"I think there's a process that takes place when we're bringing something to new hardware, where we want to of course incorporate the features of the hardware in a way that highlights what we're trying to do. If you bring two similar systems together, our experience with Metroid and MercurySteam's with Castlevania, it doesn't always result in a hybrid system that's better. In this case MercurySteam had such a great understanding of what is fundamentally Metroid that they were able to synthesize their experiences seamlessly, bringing fresh stimuli, a fresh perspective and a different set of sensibilities.
In searching for someone to help make the game, I'd heard from Nintendo of Europe that MercurySteam was interested in taking on the challenge of remaking a Metroid game. They weren't saying Metroid II specifically, but we'd heard they were really interested in a Metroid title. I of course knew MercurySteam's background with the Castlevania series, so I thought 'That might be an interesting collaboration, let's talk.'"
On why Metroid II was chosen for a remake
"Because it's an old game, it didn't feel like there were a lot of people who had the opportunity to see or even know about the baby metroid. Plus it's a tough game, and you don't see the baby metroid until the end, so it's possible that even people who played it might not have seen it. And so I thought if I get the chance to work on a 2D scrolling Metroid again, I want to go to that game."
On meeting with MercurySteam
"And so I said 'I'm going to Spain'. So we flew to Spain, met with Jose [Luis Márquez, of MercurySteam], had a lot of different talks, and I thought 'Yeah, this is going to work, let's give it a shot.' I really felt like it was a completely bullseye from the get-go. This team knows Metroid, they know what they're doing, they get it."