On my blog, the best content is in the comments. Sébastien reminded me of this fact today by offering a link to an article in Physics Today by Lee Smolin. The gist of the paper is that scientists feel a lot of pressure to follow the lead of powerful senior scientists. It is much easier to be productive when you follow established techniques. Any prospective Einstein is crushed by the system.
If you haven’t read it, I recommend Smolin’s book, The Trouble with Physics. He addresses much of the same themes in greater depth. I almost cheered while reading it in places.