Care to share an example of this ease to use with depth?
I think the more commands you got = the more depth. Make it less and you get less depth, but easier to use(More general commands) Seriously...I think the games perfect as it is with interface.
Remember when we got the feature to be able to mark blocks of walls/floors for building all at once? That improved ease of use, but didn't destroy any depth at all.
The status screen provides a nice summary of things like food stocks and how many dwarves of each time a fortress has. Without that, one would still be able to obtain that information, but it would be very tedious. Adding the status screen in no way diminishes depth.
A recent suggestion of adding contextual options to the workshops where they make sense (such as auto-loom options at the loom, butcher options at the butcher) would increase ease of use, but not impact depth.
Making it easier to select multiple items for trade would be the same.
As would a way to store a filter for which building materials to display when constructing a wall or something. Having to repeatedly scroll down to select Marble Block because it isn't the closest material (or worse, not having to scroll because it is the closest until suddenly you've used up the nearby marble blocks and are accidentally selecting charcoal) is obnoxious, and in no way increases depth.
Getting dwarves to wear the armor and wield the weapon you want them to could be improved (and apparently has been for the next version). In this case, I suspect Tarn has added both depth
and ease of use, though final judgment would have to wait for the new version to come out.
On a higher level, having tutorial missions, with in-game help and tips, would greatly increase ease of use for a boatload of new players. Maybe some elitist-type people might view that as dumbing the game down, but that's pushing it; I certainly don't see the games
depth decreasing because of it.
Finding a way to avoid dwarves building from the wrong side or building in the wrong order, and thus doing stupid things like getting themselves stuck, making not-yet-built sections inaccessible, and causing cave-ins off the side of a bridge used for scaffolding before the proper supporting piece is built would also aid ease of use, while not hurting depth. Unless you like these sorts of challenges. I don't, and they are one of the reasons I quit playing.
I could probably think of tons more if I had played the game within the past year. But hopefully the above at least makes it clear that much can be done to increase ease of use without decreasing depth.
Now for players who like challenge merely for the sake of challenge, I suppose my opinion won't make much sense. But I prefer to distinguish between interesting and trivial challenges. A good game in my view has a good selection of interesting challenges, requiring interesting decisions. A deep game like DF should have a wide variety of interesting challenges (in contrast with a good but simple game which has a narrow focus with its interesting challenges). But trivial challenges should always be minimized; in the ideal case, they should be eliminated. If a person thinks that no challenge is a trivial challenge, then I suppose we just don't see eye to eye. But such a person is usually a hardcore player, and the potential audience, even for a game like DF, is substantially larger than just those sorts of players, so it would be unwise for Tarn to overlook this. Besides, I get the strong impression that Tarn himself is not at all this sort of player. He is very much fascinated with making a game full of interesting challenges. The trivial ones are just unfortunate side effects arising naturally during development, not at all a design goal.