No particular reason - just that I wouldn't consider them 'intermediate' materials and the intention for plain IC is that only intermediates can be containerised. Other mods are ofc welcome to add any other containerisation recipes they like :)
(Tiny thing with repair packs is that you could get infinite usage out of them by containerising them, as that would reset their durability. On the other hand, that also applies to science packs as you noticed, and... all spoilable resources in SA...! I think the spoilable resources exploit can be fixed by also making the containerised version spoilable, then it will inherit the average spoil level of each ingredient, and spoil into 'Spoilage container' when its timer runs out.)