Do people even bother playing without lots of nearby magma? It seems like everyone is constantly talking about magma forges.
That's because of 2 things:
Firstly: Magma is extremely valuable. It's unlimited heat, unlimited fuel. Just a tank-full of it can provide great bounty to your fortress forever more. Charcoal is only used as a reactant for steel, it makes it so that the only limiting factor in smelting is simply the availability of the materials themselves. It'd be one thing if it simply made smelting "cheaper". It would simply be "nice to have". But magma makes smelting FREE. In fact, it makes metalworking free too. It makes the RECYCLING of metal free!!! Magma = Free unlimited fuel. Value? Priceless.
Secondly: Vertical movement is easy. It takes your dwarves the SAME amount of effort to walk up 100 flights of stairs from the bowels of the earth to the bright surface as it does for them to walk from their bedroom to the dining hall, get drunk, and stumble back to their beds again (actual distance may vary). Vertical travel provides no obstacle for dwarves compared with any other dimension.
So, given that magma is extremely valuable, and not difficult to obtain, it dominates people's strategies. In fact the ONLY reason not to immediately try to get magma would be if you were roleplaying, or had for some reason not "gotten around to it" yet, like if you're stubbornly trying to pump it to the surface rather than relocating to where the magma already IS.
From a game-balance perspective, I would actually go so far as to say that magma is "Totally Overpowered" and needs to be "nerfed" somehow. I also believe that Farming is overpowered and in need of some serious nerfing too. As is vertical travel. It should be about 4-5 times slower to go up a staircase or ramp than to step over one tile.