The previous owner of my property cut down a lot of trees. When I bought the place, some of the trees had been left on the ground to rot, some had been cut to 8'lengths and left on the grond to rot, and some had been cut into rounds and stacked between trees. Of the latter, most of the bottom course had rotted away, and a lot of the top layer was excessivly punky. THe rest kept my house warm last winter and was some of the nicest wood I ever hope to see. Dragged a couple of truckloads of the rotted wood out of my yard last summer and threw it in the dumpster, along with a lot of bugs that I didn't want reinhabiting the wood I planned to stack there. Pretty damned sad to see all that wasted heat. I remained grateful that they had taken the time to stack wood that they didn't end up using, or that would have been bug food, too. So there's one reason I won't leave wood just laying around.
Had a problem delivery from a seller who shorted me last summer. I stacked it to measure it, and ended up a cord short and a half a cord cut too long for my stove out of a three-cord delivery. I've been calling this guy regularly since May to put it right, and given him several options for doing so. Talked to him again Tuesday and he was going to drop off a check for what he owed me yesterday. Didn't happen. I'll call him again when it gets a little later. Each time I talked to him, he asked if I had measured the wood before I split it or after. Even though many folks would define a cord as split and stacked, this has given me the leverage to say, "I measured it after I stacked it and before I split it." That's another reason to stack: if you think a wood seller might have shorted you, the sooner you try to settle up, the better. And you might not have time to get it split sooner.
I also found it pretty easy to work with that way. I'd take wood off the round pile, split it, and stack it, and worked my way right down the row converting unsplit to split. I worked on it as time permitted, or quit when it got too hot or too buggy. It was March when it was cut, May when it was stacked (had to wait until the snow melted to work in that area), and late June before I got the wood split. The moisture in the wood was such that the bottom of the wood was starting to deteriorate where it contacted the ground. Had I left it in a pile, I suspect the center would still have been frozen.
The half-cord he left that was too long sat in a heap and rebuked me each time I looked at it. I stacked it and racked it, and felt a little better about it after that. It's been out in the sun and the wind all summer, and might not be in too bad a shape even though it hasn't been split. I'm going to cut it up this weekend, and get it split and stacked and the work wrapped up. I'm really glad I'll be dealing with stacked wood instead of a pile.
For the most part, I like to get stuff split asap because I want it to get seasoning asap, and it gives me a good feeling to see piles of wood split and stacked and wrapped up. But like Dave says, everybody has their own reasons for doing what they do. Sometimes there's the ideal, and then there's the real world. Gotta do what you can with what you've got.