The content of your scriptpubkey, beyond the resource costs to the network, is a private contract between the sender of the funds and the receiver of the funds. It is only the business of these parties, no one else. Ideally, it would not be subject to "consensus", in any way/shape/form-- it is a _private matter_. It is not any of your business how I spend my Bitcoins; but unfortunately, script enhancing softforks do require consensus of at least the network hashpower.

Bitcoin Script was specifically designed because how the users contract with it isn't the network's business-- though it has limitations. And, fundamentally, even with those limitations it already, at least theoretically, impossible to prevent users from contracting however they want. For example, Bitcoin has no Sudoku implementation in Script, and yet I can pay someone conditionally on them solving one (or any other arbitrary program).

Bitcoin originally had an OP_VER to enable versioned script upgrades. Unfortunately, the design of this opcode was deeply flawed-- it allowed any user of the network, at their unannounced whim, to hardfork the network between different released versions of Bitcoin.  Bitcoin's creator, removed it and in its place put in facilities for softforks. Softforks have been used many times to compatibly extend the system-- first by Bitcoin's creator, and later by the community. The segwit script versioning brings back OP_VER but with a design that isn't broken---- it makes it faster and safer to design and deploy smart contracting/script improvements (for example, a recently proposed one will reduce transaction sizes by ~30% with effectively no costs once deployed); but doesn't change the level of network consensus required to deploy softforks; only perhaps the ease of achieving the required consensus because the resulting improvements are safer.

If you're going to argue that you don't want a system where hashpower consensus allows new script rules for users to use to voluntarily contract with themselves, you should have left Bitcoin in 2010 or 2011 (though it's unclear how any blockchain cryptocurrency could _prevent_ this from happening).  Your views, if not just based on simple misunderstandings, are totally disjoint with how Bitcoin works. I don't begrudge you the freedom to want weird or even harmful things-- and I would call denying users the ability to choose whatever contract terms they want out of principle rather than considerations like resource usage both weird and harmful--, but Bitcoin isn't the place for them, and the restrictions you're asking for appear to be deeply disjoint with Bitcoin's day-one and every-day-since design, which has a huge amount of complexity in the original design for user (not consensus) determined smart contracting and where softforks (hashpower consensus) have been frequently used to extend the system.