My mother-in-law has a fridge magnet that says something along the lines of: "Before I had kids, I had 6 theories about how to raise them. Now I have 6 kids and no theories".
It's very easy to look forward and say "When I have kids, this is what I'll do. I won't be like those stupid shitty parents who do this or that or the other, because I know better. I'll be a good one." Then you have kids, and you realize what it's like to live with them, to be responsible for them, to know how their little minds work.
I'm not saying you'll definitely change your mind, but having kids changes you, and not just in perspective. Suddenly you really have to be responsible. Suddenly you have a little buddy who pretty much worships the ground you walk on. You have an insatiable urge to impress them, to teach them, to make them laugh, and to keep them safe. Also, the more kids you have, the more you bend your life around them. Not everything's about doing what you want to do, or doing it how you want to.
Also, if you're still leaving "toys" out when your kids are teenagers, they'll start to hate you when they want to have their friends over. Even when they're younger, if they want to have friends over for play dates, you'd best be cleaning up and getting dressed before their friends' moms come over to drop them off.