So they didn't fix the Wizard preparation exploit.
Gale can still cast Mage Armor and unprepare it afterwards to get a free extra spell slot. Same with every long lasting buff. They are essentially always memorized and free to use.
All non-combat utility spells like Detect Thoughts, Knock, Darkvision, See Invisibility etc. etc. are essentially extra spell slots and always available for free.
At this point, why are they keeping spell preparation in at all? It's just extra tedium of having to do more clicks before and after you cast one of the free spells. Just let Wizards have their entire spellbook prepared at all times. That's what their system aims for, really. Just like in DOS.