Balesir
Adventurer
Yep, the analysis is trivial, but look at what it means. A party of 5 characters has, by 10th level, more common items than they could concievably need or usefully shuffle, plus 15 uncommon items which, while interesting, they have no choices over and 5 rares likewise (assuming the DM was able to find 5 rares appropriate for the party and the campaign as s/he envisions it).
The original magic item system supported a place for items as party customisation space. Interesting choices around prioritisation of specific abilities in specific party roles could be made pursued. With rarity, you get all the interesting role support stuff chosen by the DM, plus player-selectable stuff that basically just gives the basic essentials (assuming you don't just play inherent bonuses - in which case commons have almost no function) in excess. The Uncommons and Rares will generally suit particular roles and abilities, and possibly even specific characters, by their nature, so the decisions by the players as a group on what areas they should bolster and what priorities they should have for defence/attack boosting and so on are pretty much moot. Basic plusses to attacks and defences can be covered by Commons, and they have more than enough to cover those with crafting/purchase so there are really no decisions left to take.
I don't detect a coherent design schema, here. The interesting party decision making and item allocation is almost completely gone. Rules as written, what you have is "magic items" more boring than ever before and a plethora of Artifacts that the DM gets to hand out as treats. In other words, back where we were before 4E segregated the Item/Artifact roles and put some actual sense into D&D items and what they were 'for'. It's an "Update" that not only managed to remove something good from the game but also managed to add nothing that wasn't present (as Artifacts) before, as far as I can see. Borked.
