FarmerTom states-
i "assume" they were pulled because well to put it bluntly.. they were essentially useless. XD
While I agree that as they were when removed, they were useless to anyone above about level 30. Other items though, such as refining jewels for example, have evolved with the game to retain their relevance. If there were skill encyclopedias for higher levels, it would help folks who turned in a lot of quests during the XP bonus weekends to catch up on their TP levels. As it is, if you are disproportionately short on TP at say, level 65 or 70 because you burned a lot of daily resets, like one of my alts did during the recent 350% bonus weekend, you finds that you cannot just grind up extra TP until you get to level cap, and then it is a slow go to catch up. Skill encyclopedias could help cover some of that.
The mere fact that I have mentioned them would imply that I can see them as something other than "useless", even it Tom doesn't. (no offense to Tom. We all see and play the game just a bit differently.)