>A change that increases the number of use cases of Bitcoin affects all users and is *not* non-invasive. More use cases means more blockchain usage which increases the price of a transaction for *everyone*.
This manages to be both incorrect and philosophically opposed to what defines success of the project . Neither the number of ways that people figure out how to innovatively harness Bitcoin's existing capabilities, nor the number or complexity of any optional transaction types that the Bitcoin protocol supports have any bearing on transaction fees. Demand for blockspace from transactions, which is just plain use - and not use cases - is what could drive up transaction fees.
On the philosophical level, as designers of the system, we all hope and work to make Bitcoin so useful, appealing, and secure that there is massive demand for blockspace, even in the face of high transaction fees. As an individual thinking only of their next on-chain transaction, it is understandable that one might hope for low fees and partially-filled blocks. Longer term, the health of the system can both be measured by and itself depends on high transaction demand and fee pressure.
If you were trying to argue that CTV is invasive because it may increase transaction demand and therefore cost users more fees, that is 1) an endorsement of CTV's desirability and 2) reveals that you consider any increased free-market competition (i.e. more demand) to be "invasive".
>I like the maxim of Peter Todd: any change of Bitcoin must benefit *all* users.
As for Peter Todd's "any change of Bitcoin must benefit *all* users", that is absolutely a reasonable thing to consider. However, in order to make practical use of that maxim, we must adopt in our minds a generic, or "model user", and then replicate them so that we may meaningfully understand a least a proxy for "all users". In reality, there will always be someone (and at this point, probably a "user" too) who wouldn't benefit from a change, or at least think they won't. Some users of Bitcoin may even want Bitcoin to fail, so we cannot afford assume that people have alignment of goals or vision just by virtue of being a 'user'.
Corey