Internet is far from useless when used right.
If people are playing in the lower levels. um.... yea you have the lead and you even researched everything before you advance in era.
but notice this: (correct me if this is wrong) Civ 4 's tech tree is the first to introduce "OR" prerequisite!!
This mean you can be really advance down 1 path and have nothing in other. like i can go religion all the way without even ironworking! While i found it funny the pathing was more diverse in early era than in modern era (late game, there are only 2 (or 3) paths. everything choke at scientific method and the other stuffs are flights and plastic.
but anyway, these "OR" prerequiste enables you to make short cuts to certain techs. Internet is really good if you are losing tech and you can short cut to it and catch up.
Internet might not be useful for everygame, and i'd probably will still vote it for the most useless as compare to other wonders. but it's quite essential in certain situations.
i think besides the ironwork being broken, the second most useless would be the Forbidden palace and the V-something (that french thing that does the same thing) i hardly notice the reduction
and the forbidden palace is particularly worse since it requires 6 courthouse to build.... lol