At the moment the whole Materia thing is still in the "checking to see if it can even a thing" stage. There's some promising results, but nothing concrete yet. There's also the fact that a lot of the funding for the project is split between it and several others like the magi-tech system from FF8.
Some of the earliest breakthroughs were from those that had been inspired by Nasu-verse magecraft, which lead to it influencing a lot of the recent naming conventions. It's why the military is known as the Counter Force and not something else, like Arcadia Corp, or something even stupider. You have to remember that Humanity is really new to the whole idea of magic, unlike the rest of the LDC. We're still learning how to chuck fireballs or call down icestorms, so pretty much anything like Materia is still in the theoretical and experimental stages.
When those system are finalized and become possible for deployment/usage, will the others race in the LDC add them to their inventory? And what be their reaction be? I imagine that since the others races are elemental based in their magic and using those system would allow them a lot more flexibly in their magic like how human magic is.
Some weapons literally cease to exist when their Girl returns to their normal state, rendering such enhancements pointless. Still others have magic that would overwhelm whatever was attempted on their items. Though some girls have managed to get "upgrades" such as additional armor to their outfits, or better weaponry, thanks to the efforts of others.
What about indirect enhancements? Like for say after a Magical Girl transform she put on additional equipment like wearing a bracelet that had a defense enhancement imbue on it. Will it stack with their magic girl abilities/stats?
As for using them as a power source? Not very many people have thought of that. Both Samael and Lucky have both been getting ideas recently because of the Core Connection (Sam because of how long he's had it, Lucky because she's a magical prodigy the likes of which come about only once a millennium) and will likely start looking into utilizing the power that's been imbued into them.
Will we be getting a chance to see Samael and Lucky trying these enchantment out in future update?