#8: Less Cruft
Cruft is a general computer term for stuff left over from past that's no longer useful. (The word supposedly originated at Harvard, where old physics equipment piled up in front of windows at Cruft Hall.) Drupal's developers have been pretty good about preventing cruft build-up in the software, mostly because of Mr. Buytaert's decision not to make major versions "backward-compatible"that is, a site you design for Drupal 7 won't work on Drupal 6 because some of the old version's obsolete technology has been removed.
Some things removed from Drupal 7 include the little-used Throttle, Ping, and Blog API modules; the "related terms" feature for taxonomy (which never did anything, anyway); and the ability to block posts that don't have a minimum number of words. Of course, every bit of "obsolete" technology has its fans, so such removals are always controversial; if you do find yourself needing those old Drupal 6 features, most (if not all) are still available through downloadable modules (see Figure 8).
Figure 8 It was a good idea at the time… Say goodbye to unused modules.