I don't know why soil pH is the preferred whipping boy of those who oppose added complexity, but it's really the easiest variable to deal with, at least, unless you run out of lime.
Anyway, I'll continue to defend added complexity in the model by referring back to the "free stuff button" problem.
Currently, stone is effectively free stuff - you almost always have far more of it than you can store in stockpiles or get rid of, and therefore, you will use it without even considering it a cost - it's free! Anything you can make from stone, you make it from stone, because stone is free - free rock mugs, free statues, free tables, free chairs, free doors!
Currently, wood is limited in supply, but still fairly cheap - you can make a huge variety of things out of wood, but really, you tend to stick to barrels and bins and beds, and maybe some charcoal, but not too much. Wood is something you can't just consume completely without any care in the world. You have to put at least some thought into conserving it for the things you really do need, because you only have so much of it in any given year.
Currently, however, steel and to a lesser extent, bronze are relatively difficult to make. You need fuel, metal that you have to find and are in somewhat limited (although still fairly abundant) quantities, and you're prone to supply shortages. You can't just build steel chairs for all your dwarves, you have to really consider what your priorities are for steel. (And also note that steel and wood are both inifinite, they're just limited by the amount you can harvest per unit time.)
Frankly, these are the ONLY concerns about resources/materials that you really have in Dwarf Fortress.
So yes, you can add a few more jobs onto the processing part, or a little more land onto the farming part, but it doesn't change the fact that it's still basically like glass when you have magma and sand or like stone - it's free stuff, you'll never run out of it, so there's no reason to ever consider it. Food is a default, automatic, easy gimmie, and will continue to be even if you have to up the number of dwarves working - most players just wind up killing off dwarves that they wind up have idling because they can't find any jobs for them, anyway, so simply assigning a larger proportion of their labor to farming is no difficulty, and if their entire supply chain is automatic and thought-free, then the problem will always remain.
This is why we need "additional complexity". It's because we need SOME complexity in the mechanic whatsoever, so that it isn't just a "push button, get food" mechanic.
I've frequently seen arguments against the farming thread based upon "this isn't a Farming Simulator", and that they don't want to have to care about generating resources or, really, anything besides seiges... Which frankly, seems like it's selling the game very short. DF's not JUST a Warhammer Simulator, either. We have to care about something in our fortress, and since, at the moment, we have nothing to really care about except whether or fortress continues to exist or not, food is as good a place as any to make the player actually have to care about resource management. Heck, this isn't even more dramatic a claim than what every RTS since the days of Dune 2 has done, or every city-building strategy game has ever done. Currently, almost everything you do is free and limitless and as such, there is nothing stopping you from ordering massive mining or construction or industrial projects without ever having to consider costs. There are hardly even opportunity costs associated with anything - all the defenses and food production you'll ever need can be set up in a single season's time, and even making more processing only means you have to wait for more dwarves to show up to do more of the jobs to make the ratio of foodworking dwarves still sufficient. It just means the fortresses have more dwarves, and the FPS goes lower.
The only way we really solve the problem DF faces is by making the player recognize that farming is not free, and that you can't just scale production forever, or demand things made completely without thinking about them.
Crop rotations (where sets of crops have to be chosen to accomidate one another), pests and pest control, and supporting fertilizer industries, all of which must similarly change in focus every time you want to produce more of one form of food over another. These make players stop and consider what they are going to need in the future, and build accordingly. They make players no longer simply respond to a shortage of one product by simply adding more dwarves to that production line. It means you have to consider either conserving on some resources or take the time to accomidate the solution to the problem.
This is what DF needs more of - a need to stop and think about your problems - rather than simply making all your problems a matter of oversight and not paying attention when your supplies started running low.
You want to know what the problem/facepalm moment/way I killed my fort I see most frequently coming up about farms is right now? "I forgot to start a farm." Farming is currently so mindless and so assured that people just plain forget the entire mechanic is even there. "Wait, you mean there were parts to this game that weren't the military or possibly mining?!"
DF is supposed to be better than this.