Honestly, most people don't even do real time-consuming projects because we honestly DON'T have much time to play. The longer it takes to set up a fort or complete a task, the less likely we'll ever enjoy it because we wouldn't be able to have fun or !!FUN!! within our timeframe/attention span. The game is reasonably paced right now and there's certainly difficulty for anyone not prepared to deal with the naturally occuring !!FUN!!, and unnatural difficulty can be applied through mods, but making resources more scarce doesn't really make things more difficult in the sense that you're in mortal danger, just more tedious and time-consuming. Less resources = less enjoyable and a longer wait for anything to happen, which sucks.
Of course, I am tackling the concept from the standpoint that I absolutely hate grindfest-type games that demand you waste time and energy on resource acquisition before blowing shit up/even encountering real problems, like being killed. I don't want resources to take more work to obtain as much as I want to take my massive hoard of legosstone and make a castle of horrors of such ridiculous complexity that I forget how to operate it, then enjoy the brand-new combat AI that makes defeating a siege far more satisfying and more difficult. I do such sadistic things as throwing a half dozen legendary soldiers against a horde of giants, because that's both fun to watch and !!FUN!! when the tantrum spiral starts because Urist mcDead was married, had a dozen kids, and was friends with everyone else. Waiting for blocks to be ready for my megaproject? No. I've been happy with rough stone boulders because I like to start as soon as possible.
The problem with that is, what you're describing isn't a game at all - it's just a construction set.
A construction set where you have infinite powers, and you just use the terrain as your canvas is fine and all, but it's not a game and it has no challenges.
The game that DF is moving towards and should be isn't something where you move blocks around for 20 hours before deleting the world and making another world again and starting over from scratch.
It should, instead, be a 300-hour project where you scratch your way up from meager beginnings to controlling a world-spanning empire, with every step along the way adding additional challenge and complexity until you are simultaniously juggling the military strategies of an army on the march, their logistical needs, the intra-court politics of your king and nobles, relations between the dwarves and their tigermen and antmen allies over the benefits of citizenry, maintaining farm production, keeping the citizens of your capital entertained with bread and circuses, keeping guild conflicts to a minimum, keeping the minecarts running on time, getting enough barrels made to keep booze production running, and making sure the mandates and moods get completed.
The tagline of the game is "Losing is Fun" because Toady
wants us to keep coming back to the same fort and world with its ever-increasing depth and personality rather than just deleting the world and starting another random one every time you're done pushing around your lego megaprojects.
The construction set things will still be there, but there's so much more game to be added onto DF.