Throughout a fairly long chess career, I have always regarded 4.d3 after 1.e4 e5, 2.Nf3 Nc6, 3.Bc4 Bc5 as a good beginner's move but not threatening, and I have felt sure that most strong players shared this opinion. Quite suddenly, 3.Bc4 and 4.d3 have become the choice of very many top players. In the recent Isle of Man tournament there were days when the top boards looked like a junior scholastic tournament (but with very few examples on the lower boards). I don't see a big difference between these games and typical 19th century games.
How did this happen? What has changed? Is there somebody out there who has been paying more attention than I have?