The more I think on it, with the exception of art direction and some other details, when you combine Fallout: Tactics with Point Lookout, both fit in better with the main canon than I thought. Let's keep the following details in mind:
- Fallout Tactics takes place between the events Fallout and Fallout 2.
- Professor Calvert's family was incredibly influential, yet they have no known connection to the Enclave.
- Vault 0 doesn't fit in with the rest of the Vault Experiment as presented.
- The Calculator was connected to human brains which were essential to its function, brains that maintained their personalities unlike typical robobrains.
- Vault 0 was located within Cheyenne Mountain, which is a smoking, radioactive crater during the events of Van Buren, which is set after the events of Fallout 2.
Rothchild says the Midwest Brotherhood was in serious decline at the time Lyon's group encountered them between (which based on Lyon's account of how long they've been there had to be sometime between 2257 and 2277). This means that some 59 years after the Midwest Brotherhood defeats the Calculator and controls a huge stretch of territory ranging from Vault 0 to Chicago, something happens to render the site of Vault 0 a smoking, radioactive crater and the Midwest Brotherhood in a state of serious decline.
Based on all that, I think the purpose of Vault 0 was two-fold: to trap the pre-War enemies of the Enclave and to provide them with a robot army to pacify the wasteland. In order to keep the true costs (which at least once ran hundreds of billions of dollars over budget) and the true purpose of the Vaults out of the spotlight, and to carry out their plans without opposition the Enclave had to give the appearance of including their opposition, so they wouldn't blow it wide open.
The Enclave allowed Vault 0 to run well over budget and to include frivilous luxuries to lull its populace, their enemies, into complacancy. Professor Calvert's advanced brain preservation technology was used to give the various Calverts in Congress the notion that their participation was vital to the cause. Then, when the vault was occupied and its populace was put into stasis, their pods were sabotaged to render them all retarded. The robots were eventually released as planned to wipe out all mutated life in the wasteland. When the Warrior and their team penetrated Vault 0, the Calculator simply lied in order to preserve itself, that the Enclave might reclaim the use of the robots once more. The Warrior declined to have their brain sucked out and so they destroyed the Calculator, destroying the robot army.
The Enclave had been around the whole time, but they only started looking for Mariposa and experimenting on Deathclaws well after the events of Tactics, this is because they needed a new way to purify the wasteland without their army of robots. Three out of five of the Enclave facilities presented in the series have included some manner of self-destruct mechanism. It would make sense that upon learning that Vault 0 had been compromised and occupied by the Brotherhood, with little chance of recovery, that the Enclave would blow up Vault 0 by remote.
The Midwest Brotherhood had a number of ghoul and supermutant members. Ghouls can go feral and supermutants exist in limited number and can become senile. The loss of these members to attrition and feraldom/senility along with the catastrophic loss of everyone stationed at Vault 0 (likely including the Warrior, who was very high ranking by the end of tactics) could easily push the Midwest Brotherhood to the brink of destruction.