They kind of reverted mantras to their original state but not all the way. You don't have to prep your mantras out of combat, they will enter the ready state on their own once they are off cooldown. If you use up all your mantra 'ammo' you will have to recharge them like before but you will gain a page for your tome as well, creating a bit of an incentive to use up your mantras. They are telling you to use your tome skills as well basically.
Mesmers mantras don't automatically enter the ready state but Mesmers mantras do 'something' while the mesmer channels them so that you want or won't feel bad for using the final charge or a mantra.
There's different arguments for or against the change/revert. Pvp did steer the change but mantras did become skeptical skills that were 'free' which I don't like Anet cared for when it came to balancing mantras in general. Believe it or not, some players even asked for mantras to be reverted because they felt like mantras had lost their identity.
https://wiki.guildwars2.com/wiki/Upc...res/2023-02-14
Upcoming changes with pictures with those of us who don't know skill names.