High Voltage Software explains why they dropped Wii MotionPlus support.
When The Conduit was announced, High Voltage Software indicated plans to incorporate Wii MotionPlus and WiiSpeak support into the upcoming first-person shooter title. However, several months passed by with no further mention of it, and news eventually made the rounds that Wii MotionPlus support had been dropped. As it turns out, Wii MotionPlus was incorporated into the title at one point, but after a couple of tests High Voltage decided to drop support of the peripheral.
Eric Nofsinger explained to 1UP that the main reason it was dropped is because it didn’t improve IR tracking, and ultimately added nothing to the experience. High Voltage hoped that Wii MotionPlus would enhance IR tracking, in addition to enhancing the Wii Remote’s motion-sensing abilities. Since Wii MotionPlus logically offers possibilities with melee weapons, they actually prototyped a few melee weapons that would take advantage of the peripheral. However, due to the game’s June release date there wasn’t time to fully incorporate them into the final product. The developers ultimately scrapped Wii MotionPlus support and these specific melee weapons.
Nofsinger confirmed that WiiSpeak support is still included, and described to 1UP that it took a lot of effort for High Voltage’s audio engineers to do so. On the bright side, Nofsinger confirmed that WiiSpeak is a fantastic fit for the game, and the efforts have paid off since it is an excellent feature for online multiplayer.