So Make Use Magic Device a skill which defines its culture
1.)Spell power disregarding metamagics should reflect on magic items with Castable spells, just like Ranged and Melee Power imbue physical attacks with additional damage not included in an items description. Though a tree should be created or Feats allowed chosen that allows a player to apply metamagics individually as acquired when using said items to further the concept of an artificer influence.
2.)Use Magic Device should allow the use of equipment of higher level if the players skill is adequate in a static scaling with ML of the item, with the player's DC of that particular school of magic and levels in either arcane, divine, artificer, or alchemist giving added bonuses in that check if applicable (this is mostly for clickies, wands, and scrolls)
*Note- Armor, Weapons, and Equipment would have a UMD check just for ML and certain criteria to meet based on effects such as conflicting alignment as these are simplified items.
Eberron is an environment rich in Magic being it is deeply entrenched in the mechanics of society, so being familiar with it would be an adaptation of necessity, progress, empowerment.
For higher level content such as Reaper Mode it seems investment in the Use of Magic to combat the challenges presented would be the mindset of natives of Eberron, not necessarily in spellcasting ability but mastering magic in their very environment in which these tools were crafted to best make use of them. It takes several lives, tomes, investments to get high UMD on classes without it. It should be used for more than just heals, raises, and teleports. It should make the magic glitter brighter on every item with its power in grasp.
I am sure there would be your primitive people, or those who shun magic in Eberron similar to this world concerning modern technology and science... but most would embrace it as essential to their existence. This online campaign setting should reflect that...