I think there are two different arguments you're proposing here:
1) Sharing information is fundamental and should not be restricted
2) Artists are being paid too well
To the latter I might respond, if you feel prices are too high, refuse to purchase the good at higher prices. Nothing is more effective than voting with your wallet. The reasons prices are that high is because people are willing to pay that much. Restricting the copywrite duration won't reduce the amount of piracy. Also, try to remember, people don't publish in scientific journals because they want others to copy, they do it because it garners grants, positions and fame.
To the former, I vehemently disagree. The idea that people should be able to gain things with no effort (here money representing that effort) is the same as suggesting people not be rewarded for their actions. If you enjoy an artist then you should want to give them money; how else will they know their efforts are appreciated.
Let me give you an example. A small company, Gas Powered Games, puts out a video game Demigod. They include no copywrite protection, no DRM, no anti-piracy. What's more they can tell when someone is using a pirated copy on their servers (its an online only game). What they see is 9 out of every 10 people playing are using a pirated copy of their game, on servers they have to maintain. Do you believe they think to themselves "well people naturally copy," or might they have said, "these people obviously enjoy our game because they're playing it, but without paying they are bankrupting our company." It seems a poor way to reward hardwork...