Ty for the replies. :]
I'd be quite satisfied with torches just being an un-interactive fluff item, until such a time as the lighting systems would be looked at more closely (if they will be). I think, at least initially, they could just be constructed with a log of wood (perhaps 1 log: 5 torches or so?) and access to a furnace or any other source of !!. Then an architect could go fit them to the walls and they'd just burn there forever without needing additional maintenance. Perhaps guards could also carry them around as part of their standard 'uniform'.
I don't see any really important reason why they should require additional labours to keep lit, as like Gazz mentioned, this would take up an annoying amount of fuel and time. But simply having them there would be amazing, IMO. I dunno, maybe it's just me; I must admit, I'm really into the whole fortress designing side of DF, and little aesthetic details like this please me greatly.
Also, on the point of Dwarves and their light-sensitivity/cave adaptation-- I must admit, I forgot about that for a sec.
Though, sunlight is very much brighter than simple torches; and I do not think any creature capable of full eyesight can actually
see in zero light, and this is where I think it would make sense to have torches (if only aesthetically, and not as an actual gameplay element). Even noctornal animals in the wild rely on the low ambient levels provided by the atmosphere, or reflected by the moon. Animals that live underground, in total darkness, are typically blind or have underdeveloped/vestigal eyes (because, obviously, it's impossible to see anything no matter how amazing your nightvision is).