Yes, it's a good point about the main tour. I think it was originally laid out in the late 20's/early 30's, at a time when you still had a lot of visitors arriving via the river-landing. So from that perspective, it helps explain, somewhat anyway, the nature of the tour route. I don't believe it had any real major changes until 2008 or 2009, when more of the western side of the battlefield was finally included.
But I think the nature of the park, and the way the battle evolved, lend themselves a lot more to confusion than clarity no matter what. You don't really have to try to get turned around at Shiloh. It's included as part of the experience.
The worst thing about it as far as creating a tour goes, would seem to be the fact that it was basically two battles fought across the same ground on two different days. So no matter what you do or where you go, you're encountering markers and monuments for both days, facing all sorts of directions. Plus, after the opening segment of the battle on the 6th, the fighting began to splay-out, with the Confederate army more or less splitting in half and advancing on two fronts at the same time.
So to create a tour in chronological order would probably require a lot of back-and-forth across the park, going out and coming back, to cover both days. The current tour I guess is kind a of compromise in that respect, even though it's not perfect. But I suppose they have to consider that most visitors to the park will only have time for an overview, so to speak.
All that said, I still agree with the original point. I'm just not sure there's a better alternative. That's why they don't offer to pay me the big bucks to figure it out.
Perry