There is a social contract with the user base, most of whom are using it as a store of value.  Some might not like the SoV use case, but it happens to be dominant.  OP_CAT combined with OP_DUP can exponentially increase the memory usage of all the nodes, up to a limit.  As memory is more expensive than disk, it's a bit like a block size increase in terms of using resources.  Question is whether the use cases justify the risk, and also the risk of a contentious chain split.  I am sure many of bitcoin's enemies would stir the pot there.  OP_CAT is already enabled on liquid and no one uses it.  I think they should show the user base how amazing it is in demos, and if the users say, "wow", that is a better argument.