I was severely disappointed with the idea that I need to go hunting for Lapis Lazuli for enchanting. Even if it's available from villagers, it's still a rare enough commodity that it drastically limits the ability to enchant. While it's nice to know ahead of time what enchantment you can get, you still don't have complete control over the enchantments you are allowed. Sure, if you have a fortune 3 pickaxe, you can get some hefty returns from the lapis lazuli ore you do find, but you need lapis lazuli to enchant in the first place! Catch 22!
Why not just merge the two mechanics together? If you don't put in enough Lapis Lazuli for the option you want to select, then instead of the option giving you a hint, the option is left hintless and provides an enchantment that is random and unrelated to the hint you would get if you did put lapis lazuli in. This allows you to conserve lapisAs a bonus, using the random enchantment method from 1.7 could be made to still push the enchantment seed to its next iteration, allowing you to get different controlled enchantments without having to waste lapis lazuli.