If thats your logic then why patch the game from its original form and play it as is? Maybe it was something that was simply overlooked. I find it hard to grasp that making you constantly drag things to your buttons is part of a playstyle considering you can simply macro that. Most games and their rules are vastly different from one another when it comes to changing in game options for QoL to the user.
D2/D3/PoE and most hack n slash games will not allow the user to alter the ui or add more buttons for more skills. Why? No fuckin idea lol. Then on the flipside with WoW/ESO you can pretty much change whatever you want, the ui, keys, more buttons whatever the user needs. The cool thing about Neocron you can already change alot with the ui with simple config changes so just making couple of slots universal for 2 items would hardly be game breaking.