God works in many ways. How can we say with any certainty that we know what is best? We have evidence of old earth. And i have seen many videos connecting the old earth theory to the book of Genesis.
My position isn't really affirmed yet, but on the subject of New Earth vs Old Earth, I'd have no trouble accepting wgat the modern scientific position is on with the age of the earth.
I believe in an old earth but that God created humanity about 6,000-10,000 years ago. I actually held to a young earth until I studied it out and came to believe that the Bible teaches an old earth. I hold to what is commonly called the Gap Theory.
I'm definitely a young Earth creationist. I tend to believe the scientific evidence is in favor of a young Earth. Anyway, I did a debate on this, you can view it here: http://www.debate.org/debates/Evolution-vs-Young-Earth-Creationism/1/
If one accepts the Biblical account as true, then it is incompatible with old earth \evolution of animals. The best reason for this is the types of animals are out of order from what evolutionary science proclaims, so once you start down the path of modifying the definition of words like "day", then you have started down a slope of doubting the next concept and the next and may as well throw out the entire book!