Seems like Miyamoto really didn’t want to make a Mario World sequel after all:

EDGE: “We remember the glory days when the Super NES was first
launched, with titles like F-Zero, Pilotwings and Super Mario World.
Why did Japan never really exploit those games with sequels of equal
weight?”
HL: “I think there are sequels for these games – let me put it this
way, there are a number of games that Nintendo work on which do not
see the light of day, because we’re measuring the games that we’re
working on against the same quality level. There may be sequels which
I cannot tell you about or they’re simply not public. The other reason
is that people like Mr. Miyamoto are not told: ‘Okay, you are now
going to make a sequel to Pilotwings.’ That’s not  the way we treat
our creative people, for good reason. So a lot of it has to do with
their own choice as to what they want to work on.”

And then there’s the “3D experience”:
EDGE: “There are arguable three major problems associated with the
Virtual Boy. …And thirdly, the 3D effect alone doesn’t actually
bring anything new to the gaming experience.”
The response is very long, so I’m not gonna type it all out, but
basically, he says that it offers the “3D experience”, which makes me
wonder whether the 3DS software will be about more than just the “3D
experience”.

This is an excellent ‘blast from the past’ email.

I have nothing to add. It speaks for itself.