What is this revised calendar system?

Here's been my idea since I was a kid and learned "Thirty days has September..."

I've always wondered why February has only 28 days,
while 7 other months have 31. Long ago we couldn't have robbed 2 months of a 31st day and given them to poor February?

If we're going that far, why not make every odd numbered month have 31 days, except January, which gets a 31st day every 4th year?