Because creation is important, especially Genesis 1 & should be read literally as should most of the Bible really.
No, it's not a matter of "the Bible
should be read literally", but, "is that what the authors intended?"
Did John literally mean that Jesus is a gate, a vine, bread, light, a lamb and so on? No, not literally; he was a man. God also, of course, but flesh and blood, not foliage or wood.
Did Jesus literally mean that we should cut off our hands when we sin or pluck out our eyes when we look at something that we shouldn't look at? No. We could only cut off one of our own hands and only have two eyes to remove anyway - and we are all going to sin more than 4 times.
Did Jesus mean that it's easier for a literal camel to go through a literal needle than for a rich person to enter the Kingdom of Heaven? No; that's impossible.
Did Paul literally mean that anyone who taught that circumcision was necessary should be castrated? No.
Is the sun literally in a tent in the sky? Are we literally sheep? Is God literally a Rock? No.
There are plenty of things in the Bible that are history, are true and actually happened.
There are other things which happened but which have been written as poetry; with poetic form, language and so on. That doesn't mean we can't learn truth from them - the parables may not have been literal events, for example. They still teach the truth, but the words are not literal.
So the meaning of Genesis 1 - and I've said all this before - is that God created the universe. GOD - not chance, not an angel, not a different god for every day, animal or plant. God, our Creator, made everything.
It doesn't tell us how he made it - God has given humans the ability to learn, discover, question and find out for ourselves. Scientists do this - but they didn't create the universe; God did. Genesis doesn't tell us how long God took to create the universe. It says 6 "days", yes; but it does not say that each of those was literally 24 hours long.
So creation is important because this is GOD'S world, he made us also and gave us the job of caring for it. Those who don't believe that probably won't care much for it and may behave as though there is no God.
But it's perfectly possible to be a Christian; a Spirit-filled, Bible-believing Christian and believe that the earth is the shape that scientists and astronomers have discovered it to be. Saying that the Bible is a globe, does not contradict Scripture, it does not mean we don't believe God, or treat his word lightly or anything else.
Nor does it mean that there is some great conspiracy and some fraudulent, lying Christians, egged on by the devil, got together and said "let's fool everyone and pretend we went to the moon, that Antarctica's a big place or that the earth is a globe." That is a ridiculous attitude and does a Christian's credibility no good at all.
Why should non-Christians believe us when we talk of things that cannot be seen; God, heaven, eternal life, if we can't even tell the truth about things which can be seen?
And your teaching requires people to believe that the earth is a flat disc, suspended in a square - 4 corners of the earth - at least 40,000 feet deep and with a ring of ice around the edge which is called Antarctica. All of that can be disproved. You have no answer for the scientific evidence, artefacts and pictures which do disprove it, so just wave your hand and say "oh, they're all liars."
Not a good Christian witness at all.