I've been playing a couple of games now, trying to use scouts in a meaningful way. Here are the things scouts may be useful for as far as I can imagine:
(1) Scout an unknown map, so that one can decide in which direction to expand most aggressively. (2) Gain insight into enemy territory, to see where crucial production happens etc., so that attacks can be planned better. (3) Reveal a specific enemy military building from the shadow of war so that it can be attacked.
The problem with (1) is that the scout's hut is essentially as expensive as the smallest military building. Since scouts also consume rations, and their radius of action is just kind of okay, that's not a very attractive option. In the end you want to expand anyway, so why spend energy on scouts?
Scouts are somewhat useful for (2). However, they re-scout only very hesitatingly, and there's no control over where to re-scout, so that limits their usefulness.
For (3), we'd definitely need more control over the scouts.
Maybe I'm just stupid and there are some tricks to make scouts more useful, but I'm just not very happy with the current state of things. The thing is, in Settlers I always used scouts, since they just work like geologists do. I find myself using scouts almost never in Widelands, and that's a bit sad.
At first I thought, it would be nice if scouts worked more as in Settlers. However, then I reexamined things again, and now I wonder: Why not change scouts to work like soldiers? Simply click on any field (or perhaps any field that is visible, but may be under fog of war), and you have the option of calling a scout there, provided that there is a scout in a scout's hut within a certain (large, perhaps 30 fields or more) radius, and a ration is available in the scout's hut. Once called, the scout will go to that field and continue exploration around that field.
That way, you'd build a scout's hut relatively early in the game, and just call the scout to where you want to explore. What do you think?