Redstone is by design made for implementing logic, so it belongs to slightly different category. Although I think Redstones introduction was prompted by people building logic without it in the olden days.
I think Redstone's inspiration was people building computers in Dwarf Fortress with floodgates and pressure plates, rather than Minecraft specifically.
Dwarfputers are a wonderful tangent of their own, with a not-unlikely possibility of flooding your entire computer with firey death in the form of magma in some of the more impressive approaches - this has been possible (but quite difficult) for some time, more recent game versions have made non-fluid based logic gates[1] more realistic and usable.
Someone has built an (admittedly simple) space-invaders game[2] using df which is rather impressive.
Back in the day I used to build single-shot logic using sand supported by torches holding back water. Water knocks out torches, sand falls releasing more water, etc. When redstone came along everything got much simpler :-)
I miss the days before command blocks when it was still just about getting clever with good old redstone and a couple gates. The piston update was massive. I've built some ridiculous contraptions such as color displays and tape reels and programmable mob traps and variable-clock-rate machinery. And how could I forget minecarts... And IndustrialCraft took all of this to the next level. Wow, I miss the golden days of Minecraft.
