An RPG Inventory System

This is mostly just hypothetical since Riot would have to do a good chunk of work to just try this, but read on if you're interested or hoping for a LoL 2.0.

A lot of item imbalance comes from classes abusing items meant for other classes (see BoRK and Relic Shield). I think the restrictions of an RPG inventory system would both remove abuse cases and add build path variety. Here's my hypothetical inventory system. It's pretty much the generic RPG item system, but I'll write it explicitly anyway:

An RPG Inventory System
Champions have different item slots; the generic ones being head, legs, chest, boots, main hand, off hand, and accessory. Two handed weapons take up both the main hand and off hand slot.

Armor, weapons and accessories are split into different categories. I'll borrow WoW's armor classifications, which are cloth, leather, mail, and plate. A few weapon classes might be one handed sword, two handed sword, staff, bow, and shield. Accessories might be split into ring, necklace, and trinket.

Items wouldn't build out of multiple other items. Instead they would just be upgraded directly. Upgrading them would have both a gold cost and level requirement. The upgrade path would not be linear, rather it would be a tree. For example, a tier 1 bow might have 3 different upgrades available at level 6, and each of those would have another 2 upgrades at level 11. Upon reaching level 18 each max-tier item can also be enhanced. The enhancement would be item-specific rather than slot-specific. So not like how current boots can all have the same enchantments, rather Boots of Mobility might only be allowed Alacrity, Captain, and Homeguard while Berserker's Greaves might only be allowed Furor and Distortion.

Different champions are restricted do different categories. For example, ADCs might be restricted to bows, leather armor, and rings. Meanwhile tanky dps would be restricted to two handed swords, mail or plate, and necklaces.

Why I Think This is a Helpful System
The obvious pro is that it makes it a lot easier to balance items. You wouldn't need to worry about ADCs abusing BoRK because they're not allowed to use it. Because of this, you can also introduce a lot of different items with a specific class's needs in mind.

With the upgrade and enhancement system I mentioned it lets you customize your build to your exact situation. For example, do I want to take the Infinity Edge enhancement that lets me deal another 20% increase crit damage, or would I rather have the one that gives me 20% armor pen. Or maybe I'd rather go with a Bloodthirster instead.

An obvious drawback is that it doesn't let you try different builds. For example, if Ezreal was restricted to bows then he would be denied the choice to go AP. An easy solution to this is just to make both AP and AD weapons available within each category. The weapon categories would be categorizef by the range of the champions they're meant for rather than thematically or whether they're physical damage or not. So there would be AP and AD versions of staffs, bows, one handed swords, two handed swords, and shields.

Conclusion
Like I said, this is just a hypothetical idea. I'm interested to hear what people think of a revamped inventory like this.