No Time To Die wasted Blofeld once again, but his cameo could have been far more impactful with one key change. SPECTRE are Bond's most famous enemies, to the point that it's easy to forget that they essentially disappeared from the series for over 30 years. This was due to legal issues involving the novel Thunderball and the rights to use Blofeld and SPECTRE, which weren't resolved until 2013. What should have been a joyful homecoming with 2015's Spectre proved to be a major disappointment, as the sequel's handling of the organization and Blofeld (Christoph Waltz) felt utterly lacking.
For a time, it appeared Christoph Waltz's Blofeld wasn't returning, with the actor himself stating it was tradition to recast the iconic villain with each new appearance. No Time To Die dropped this tradition, with Blofeld - who in this continuity is Bond's foster brother - appearing in a couple of scenes, including a prison cell standoff with 007. It turned out this was a ruse by true villain Safin (Rami Malek) to kill the SPECTRE leader, but the scene itself was strangely lacking in suspense and failed to pay off the Bond/Blofeld rivalry. However, the film fumbled the perfect way to reintroduce (and kill off) the villain.
Blofeld Should Have Died With SPECTRE
No Time To Die's MacGuffin involves DNA-targeting nanobots that were originally developed by MI6 but later stolen by Safin. It's shown off in all its glory during a sequence in Cuba where a retired James Bond has agreed to help the CIA on an operation. Bond arrives at a secret SPECTRE party, only to discover it's a trap designed to lure him to his death. SPECTRE unleashes the nano-virus with the intent of killing the former 007, only they start dying instead, as the nanobots were reprogrammed by Safin's people. It's a great reversal, but Blofeld should have been there too.
SPECTRE never quite gelled in the Craig era, but it was still shocking to see them so abruptly killed off. Having Blofeld suddenly arrive and deliver a speech to a stunned Bond not only would have added to the sequence's power - considering the supervillain is supposed to be in prison at this point - but having him die so early in the narrative would have been the last thing viewers expected. Not only that, it would have again set the mask-wearing Safin up as a powerful foe, and not having to visit Blofeld in prison would have knocked about 15 minutes off No Time To Die's sluggish middle act.
Why Christoph Waltz's Blofeld Didn't Work
Alas, it was clearly felt that having Blofeld in prison and playing a Hannibal Lecter-style role in No Time To Die was more powerful. On paper, casting Waltz as Blofeld should have guaranteed a fresh take on the classic 007 antagonist, especially after his Inglourious Basterds turn. An issue with his Blofeld is partly that the actor underplays it to the point of being too subdued and casual, so he exudes little menace. The other is the writing, as the reframing of Bond's past adventures as revenge by his "brother" Blofeld makes him feel like less of a criminal mastermind, and more of a jealous, petty little dweeb.