Magical protection could trump the Taboo.
Ron says early in Deathly Hallows that the Taboo breaks protective charms.
“Sorry,” said Ron, wrenching Harry back out of the
brambles, “but the name’s been jinxed, Harry, that’s how they track
people! Using his name breaks protective enchantments, it causes
some kind of magical disturbance — it’s how they found us in Tottenham Court Road!”
Harry Potter and the Deathly Hallows - chapter 20 - Xenophilius Lovegood
However, it's made clear later on that advanced protective charms such as the Fidelius Charm are immune to the Taboo's effects. You give this example of where the Taboo might be useful:
Or when him and Ron were surrounded by Acromantula.
However, Hogwarts (including the Forbidden Forest) is under the protection of a powerful Anti-Apparition charm, along with many other protective enchantments (the only way the Death Eaters could get into Hogwarts was a broken cabinet). It is true that Dumbledore could've disabled the Apparition prevention temporarily, but it's likely that there is other protection placed on the castle that would work against the Taboo, and lifting many protective enchantments at once would be risky for the castle. Similar protection would've been placed on the Ministry, and possibly in the graveyard.
Lord Voldemort would expect to be aware of the Taboo.
Once Lord Voldemort was revived, he met again with Severus Snape, who was supposedly working as spy at Hogwarts for the last few years. If Harry pulled out this trump card without Voldemort's knowledge and summoned members of the Order during a fight, suspicion would certainly be cast on Severus. Also note that if this idea had been executed in Harry's first year, Harry would likely have shouted the Taboo when he met Quirrel, making Voldemort aware of the Taboo early (even if the word was changed, Voldemort would know to take measures to prevent a Taboo from being used) and otherwise not making a significant difference.
Once the Death Eaters were made aware of the Taboo, it would be easy for them to make it ineffective using a far-extending Anti-Apparition charm, or using a Tongue-Tying curse to prevent Harry from speaking (note that in the graveyard Harry was physically prevented from speaking most of the time).
Note that Voldemort has more experience in Dark Magic than Dumbledore — if one supposes that Voldemort would not recognize Harry's actions as triggering a Taboo, it would make sense that Dumbledore wouldn't have thought of using a Taboo in the first place, which seems like a good reason why he wouldn't set one. It's most likely that Harry would use it in the middle of a heated battle (breaking any basic protection like Shield Charms that was being used), making the effects of the Taboo more recognizable.
Dumbledore doesn't want to use Dark Magic.
The Taboo seems like Dark Magic to me, considering it essentially stops people from saying a word, not to mention the fact that it breaks protective enchantments. Dumbledore does not use Dark Magic when possible.
'You flatter me,' said Dumbledore calmly. 'Voldemort had powers I will never have.' 'Only because you're too – well – noble to use them.'
Harry Potter and the Philosopher's Stone - chapter 1- The Boy Who Lived
Using/relying on the Taboo would be risky.
There are multiple dangers inherent in using a Taboo for this purpose (though not all of these are things Dumbledore would be aware of):
- It could be used by Death Eaters/Lord Voldemort to lure Dumbledore and the Order into a trap.
- The trio of protagonists could grow over-reliant on the Taboo and fail to gain the necessary combat experience (though to be fair they really only survived because of their sheer dumb luck). For this reason, they would be more vulnerable than usual if they were prevented from activating the Taboo.
- The Taboo could be used at the wrong time. Imagine if, upon seeing Sirius Black in the Shrieking Shack, Harry shouted Bumdingerino, and Sirius was being subject to a Dementor's Kiss twenty minutes later. I do not believe this would happen, but it is certainly a possibility.
- The usage of the Taboo could encourage Lord Voldemort to think more and execute smarter plans, like capturing members of the Order of the Phoenix or keep them all occupied with different things so they could not appear to protect Harry.
- Similarly, placing a Taboo may give Lord Voldemort the idea to use a Taboo of his own, for example putting one on his own name. Bear in mind that just because this occurred anyway doesn't mean that Dumbledore wouldn't have took this into account when thinking about such an idea.
- Apparating long distances (the graveyard is said to be about 200 miles away from Harry's home and more than 100 miles away from Hogwarts) runs the risk of Splinching, especially if done frequently.
We don't know the limits of a Taboo.
We've only actually seen one example of a Taboo. It's quite possible that there are limitation to this spell that we don't know about. Perhaps it can only be used on names, or perhaps two Taboos can be placed on one word. We also don't know who is in charge of the Taboo placed on Lord Voldemort's chosen name, and (as The Dark Lord covered) it's possible the Taboo is an advanced spell like the Trace that is difficult to cast or requires multiple people.