Wizards now have the same spell progression table as cleric, they must still learn spells from scrolls - but it really didn't make sense in the NWN environment that wizards wouldn't have as many spells they can memorize as clerics. In table top, they get more due to being able to use all the spells in the game and plenty of customized fights curated by a DM. In NWN, you have more fights, less curation and less spells.

As always, this balance change will be watched and could change based on feedback.