Yes and no. Yes, it's better. But, it was always a fairly meaningless ability. So making it slightly more meaningful doesn't help nearly as much as someone who gets actual high level wizard abilities. Which are higher level spells. After all, at level 10 they were already getting 21 spells a day. More than enough for the number of combats and rounds in a day, particularly in first level spells. Just how many times do you think Wizards will be targeted in a day where they need higher AC? It's not like those spell slots are being used for magic missile anymore, they're already there for shield and absorb elements.
I understand the point but I think we are isolating Wizards as a corner case when this is realistically a common theme of class capstone esque abilities. For example the monk, sorc, warlock, and bard capstones all work in a similar way, they don't add "power" they add "longevity", the ability to maintain your class stuff for a longer duration.
Then you have the Paladin who just gets a wider range aura, a more "useful" aura but not a more powerful one.
The cleric's divine intervention is pretty solid, but if we make the assumption that it only allows for 5th level and lower (aka the maximum spell he can cast), then its a very flexible extra spell slot....the real power then is the ability to pick any cleric spell or domain spell and use it. Wizards already get the extra slots with their short rest refresh, so its really the spell flexibility that is the power of this ability. Solid, but I don't think clerics were the dominate spellcaster before either.
Rangers do get a nice capstone, but since they are generally considered one of the weakest classes, seems like they could use the help.
Fighters, I've already argued that their second action surge should not be allowed in the same encounter. This again will give us longevity but not nova power. They are not getting their actual capstone, which would be broken in this system. And I personally think the AC and saving throw bonus is unnecessary, they have an absolutely solid package at the moment.
Rogue's capstone is nice, but its once per day and only makes them a little more consistent on their attack rolls. The 20 on an ability check is probably the better use, but a super skill roll is not going to break the game. That and elusive give you a nice high level package, but competing against 5th level spells I don't think its anything to write home about.
The druid's capstone is broken, and I've argued for a 1 minute cast time between uses to get the unlimited effect. Again longevity instead of power.
So that leaves the barbarian, who you could argue has the best overall capstone (out the druid of course)....and perhaps could be toned down as a +2 str and con or something of that nature. I think the argument could be made that the barbarian is one of the biggest winners overall with this compression.
So back to the wizard, yes they don't get 9th level spells....but its not like every other classes is knocking it out of the park in power. They still have the power of 5th level spells, still get a lot of spell slots through their recovery, and now can casually throw around a 2nd level spell. That's solid, not mind blowing, but they didn't suddenly get dropped to the bottom of the pack either.