I feel like these should be added to the list of spells that require an extra component to craft. Mechanically speaking, Mordenkainen's Disjunction is one of the most overpowered assets in a character's arsenal, and everyone at high levels carries them. The dispel cap doesn't really mitigate its signature effect, which is to automatically strip six of a character's defensive wards. Harm, SoV, and True Sight Scrolls, which require components to scribe, are generally much more tame by comparison.
The argument can be made that if you play smartly, you can prevent your opponent from breaching you, but, like, whatever. That applies to a lot of things, including several of the scrolls that are classed as powerful enough that they should require a component (e.g., Harm).
Edit: I made this post under the assumption that the additional crafting components for certain scrolls were Arelith-specific, and were thus decided on under the assumption that those spells are powerful enough that they should be restricted in some way. If that's not the case, then I might not be as wedded to this suggestion as I was when I originally posted it.