Thing is, they're not easy to lose, you only lose them if you convert or consume them.
You're often put in a scenario where you have a choice between winning the mission by converting the item (or desecrating the glowing guardian, as the case may be) or retiring to preserve the item. It's an unfun choice: sacrifice a powerful item and be forced to do significant grind later in order to get a chance at winning.
I know I often would shell out loads of gold in the alpha because I needed an item to squeek off a win in a difficult scenario, which meant some grinding after the fact to get it back. In beta, the grinding to replace a lockered item is much much
longer and I'm actually more inclined to retire than go for it.
This factor also makes the current glowing guardian's desecration penalty far too steep. For anyone bringing locker item preparations (which, on a more difficult scenario, is always
), you'd rather lose the mission than lose the item.