i reckon it's all marketing, they have managed to sell people on that more gears is better so now if shimano can release a new 30 gear system they can rave about how much better it is than campagnolo's that only has 27 gears and then campag will make a new 33 gear system etc etc
Cheers Ed
Just as we moved from manual to auto transmission for cars, the desire to have smooth shift to accommodate varying terrain while maintaining cadence called for more gears. Shimano invention of indexing led to this progression. Its however good to see development work where numbers are being reduced and still maintain that smoothness.