So, with the release of HOT and the focus on fractals as the primary 5 man cooperative content in GW2 now is surely a really good time to overhaul the rather patchwork and often confusing (especially for new players) approach to infusions, while at the same time implementing a sensible and useful level 500 jewellery crafting system.
These two birds can be got with one stone by doing something along the lines of the following suggestion.
Primarily, remove the defensive/offensive/utility infusion slot from the game completely.
On weapons, armour and un-infused ascended accessories replace it with an agony infusion slot (the +1 to +16 ones).
On infused ascended accessories replace it with an inbuilt +5 AR.
On all ascended accessories remove the inbuilt stat bonuses and replace those with a normal gem/jewel/universal slot (the same as how exotic and lower accessories work).
It is very important that this be done in such a way as to not penalize players for investing heavily in these slots by returning any mats used (the many T6 mats for those +5 power/precision etc infusions being the most important).
Make those of these items that are desirable to keep in the game (utility infusions, WvW infusions) into ascended universal upgrades (with a 1 per character restriction, ala ascended items in general, and minus any AR).
There are many advantages to doing this. Firstly you greatly streamline the AR system, and completely separate it from item stats. This makes it a lot easier for players to understand, and separately pursue both AR and max stats on their gear without having to invest in either one if they dont want to. It also creates more consistency across all ascended gear, and more consistency across all accessories.
Secondly by replacing those AR slots with a normal upgrade slot as seen on exotic and lower accessories you create a space for crafted ascended jewellery items.
T6 precious metal (electrum?) created from lower tier precious metals (silver, gold, platinum etc),
T6 gems, created from lower tier gems,
T6 jewels created from T6 gems and T6 precious metal
T6 universal upgrades – any infusions converted to upgrades (utility infusions) as well as T6 versions of normal universal upgrades (seals, medallions etc) since those are currently useless and unused so this could be a good way to bring them back.
Since ascended accessories themselves are all named and unique and have many methods of acquisition already it doesn’t seem advisable to also make them craft-able, so by doing things this way you have more than enough items for grandmaster jewellers crafting without requiring that.
Its pretty clear that the initial implementation of AR was rushed, and the last revamp (which added the Agony resistance slot and the +1 to +16 AR infusions) is a vastly superior one that was introduced to help fix it. Now that we have had the new system system in place for a while now there is no good reason to keep the old one and as you can see essentially replacing the defensive/offensive/utility infusion slots with ascended jewellery slots would provide benefits all round.
Thank you for taking the time to read this feedback, hopefully it was of use to you and I wish you the best for the Heart of Thorns release, and that it be as successful as your hard work deserves.