Making True Strike a bonus action would make it too powerful for a cantrip, but I think there's room in the game for a 1st-level version of the spell that is more like Shield in design.
Truer Strike?
I don't disagree. Concentration is a wonky unnecessary way to limit buffing. And, True Strike shouldn't require concentration. It should just be the next attack. The player already blew off an entire action.
After all this discussion, nobody has mentioned what I think is the single most effective 1st level spell a Wizard has - Faerie Fire.
agreed.
I don't know that I would be horribly opposed to it being a bonus action cast and it affecting your next to hit roll. I've not done a lot of thinking about that, but you can already get advantage with a familiar pretty easily, and it sucks up a bonus action that could be used for a little more serious spell (flaming sphere control, expeditious retreat, etc)
Or even bonus action/grants advantage if you have disadvantage.
As you can see, the ones that require concentration are:
Bigby's Hand
Dispel Evil/Good
Flame Blade
Mordenkainen's Sword
Ray of Enfeeblement
Scorching Ray
Spiritual Weapon
Vampiric Touch
Witch Bolt
Witch Bolt does become more powerful, but I think altering it to allow a saving throw on subsequent rounds, but removing the action restriction would counter that a bit as well.
But I also have a player with a wizard who really likes the spell. He's new, so 'doesn't know any better' but on the other hand it's a cool spell in its basic effect and even 1-2 rounds of decent damage has really helped.
Ilbranteloth
See, to me, this is just an excellent argument for how ridiculously over-powered wizards were in prior editions. Someone who can, whenever they want on a limitless daily basis, turn invisible and fly anywhere (and eventually do the same for their companions) - what does this do to the world and so many typical adventure concepts?
"You reach the creaky drawbridge of the ancient castle's ruins. You hear the howls of numerous monsters roaming the crumbled remnants, unsure of what threats stand between you and the sacred dagger kept in the top room of the highest tower... Oh, I see the wizard has simply flown up to the top room while invisible, grabbed the dagger and flown back down to the party. Alright, adventure over! Thanks for coming!"
The updates to spells in 5e have been desperately needed for a long time. (Personally, I think there's areas that are still sorely overpowered - Teleporting out of danger in the blink of an eye is just ridiculous to me, no matter what level you are... why is the casting time for Teleport not something like 1 minute, or even '3 rounds'?... I digress).
Wizards can still be massively effective. Like many other posters, I just don't see where KD is coming from. Wizards shouldn't be balanced on the basis of damage alone as their schtick is awesome game-changing spells, which they still have in spades. If you want examples, here's a couple:
- The party needs to infiltrate a system of caves filled with orcs. Rather than hack their way through dozens of orcs, the wizard casts Disguise Self on himself, dresses up the rest of the party as his 'prisoners' in a wooden cage on the back of his wagon, and rolls right through all the orcs' guards.
- An evil villain has the princess hostage, he demands the party hand over the 'Holy Scepter of Bobbybob' in return for the prisoner. The party could never give up this holy relic. The wizard steps forward and opens a small bag, showing that the scepter is inside, which is really just a Minor Illusion he created (this is just a Cantrip!). The villain releases the hostage and grabs the bag eagerly. By the time he realizes he's been duped, the princess is safe.
- The party is captured by the guards of a tyrannical king for spreading rebellion. A sympathizer inside the castle comes to save the party, disguised as a guard, he frees the party from prison and piles them into the back of a wagon to hide under some bushels of wheat, but as the party is getting in a guard walks in on them. The Wizard casts Charm Person and asks the guard to be so kind as to just look the other way and go about his patrol, and the guard grudgingly obliges.
- The party is trying to infiltrate a cave complex filled with gnolls to retrieve an ancient relic rumored to be found there. They encounter a patrol of gnolls on the way that they dispatch. On the group's leader they find a note, but are unable to read the language. The Wizard casts Comprehend Languages and reads the note, which says, "the great gathering of the tribes is in 3 days, have your group ready to leave in 2 days". Thanks to the Wizard, the party realizes they can just wait 2 days and not have to cut their way through 50 gnolls to find the ancient relic.
I could go on, but these examples are just making me eager to play a Wizard now...

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.