One of those promises is the block reward .... Another promise is that scripts in the blockchain will be executed faithfully and not overridden. Value transfer in Bitcoin is either governed by the scripting language or it's governed by something else.
Cost/benefit analysis is frequently non-linear. What Bitcoin needs rather than a bunch of cost/benefit calculations is a well-thought-out set of core value statements that the community can refer to in order to overrule decisions that look like good ideas in the moment but lead toward a zero NPV in the long term.
Putting aside the lame insult about being mentally equipped, I guess you're talking about coinbase reallocation or erasure. I was actually thinking of the getutxo message.
Still, whilst I agree we could really use some organising principles to cut down on circular arguments on github, I think your thesis about NPV is incorrect. The core goal of Bitcoin is to make digital cash that can't be double spent. Everything else it does is just a way to achieve that end goal, there is no higher principle than no double spending. Yet, we see double spending with miner cooperation and the NPV of Bitcoin does not fall to zero.
Another example; you mentioned "scripts must be executed faithfully". P2SH outputs have scripts that are designed to always evaluate to true under the original rules when presented with the right redeem script, regardless of whether the transaction is properly signed or not. Later versions of Bitcoin added a special new rule that said outout scripts of the P2SH form aren't really scripts at all, they're just pattern matched and processed using special rules. This directly violated your principle that scripts will be executed faithfully, but NPV did not fall to zero. And why should it have done? Script is a relatively minor technical detail of how Bitcoin works.
In fact the whole purpose of a "soft fork" (as used to introduce P2SH) is to trick older clients into thinking a block is valid when in fact according to the majority it isn't valid, which is one reason I don't like them and don't think we should do them. But we've done them in the past and the sky did not fall.
Regardless of what we may like to believe, all the evidence suggests that most people see Bitcoin as merely a convenient way to move money around, not a manifesto or constitution. The rules have been broken before and probably will be again in future.