I understand that the difference is huge but, The racing book: 1. Cost them money. 2. Had no other effects. Only negative. Some players stole the gear that others paid for. Thorn: 1. Was the meta. 2. Bungie apparently needs a lot of time to analyze the data they receive to make changes to the game. It took 3 months to get a simple sunbreaker nerf. Changing the racing book was a simple question. "Should we change this so we aren't being stolen from?" "Yes." Changing thorn or sunbreakers though. "Should we change these things?" "Let's see what the community thinks." "Community says yes." "How should we change?" "Let's see what the community says and look at all the data coming in about these things and do our own internal play tests." It's just a bit longer of a process.