The situation with Allied and Centurio seals is for the most part fine. You can only get earlier content related items with it and a few other bits and pieces. The difference with Sacks Of Nuts though is that there is no ongoing spent item to get with them- The Allied and Centurios can both be exchanged for Aetheryte Tickets and Retainer Ventures- and obviously it doesn't make sense to paste this over to the Sacks Of Nuts. The Nuts are very limited in use after you've done all the Shadowbringering that comes with a players time in that part of the game.
I have an idea however, how this item can be used to fix another issue, taking care of two things at once. In lieu of creating another, unique type of repeatedly-expendable item that gets bought and churned like Tickets and Ventures, I think Nuts could be employed as a means of helping ease the accessibility of older content as it ages, which will help in regards to future major patches (DLCs).
Simply put, Sacks Of Nuts could be used to buy the books that are exchanged for Eden Raid Gear. I would say a good measure could be that 400 Sacks Of Nuts could be exchanged for ONE Book of Eternity/Litany/Furor/Refulgence and so on. Keep in mind that Sacks of Nuts are still very hard to collect, unless you want to grind all the daily Nutsy Mark bills or manage to get on a hunt train- even after which it would still take you a very long time to get all the books you need to get even just 3 pieces of gear you want- a single chest piece or weapon would thus cost you 3200 Nuts. I do not seek to devalue the work needed to get the books through doing the Savage Raids, but the books are far from the sole reason people do these Raids- and the books aren't really considered valuable by those who grind Savage Raids regularly (proven by the fact they keep doing them beyond as many times as it would take to get any needed books, if that's what they were after).
I feel that this concept should too be applied to the Alexander and Omega Raid gear, but of course at a steeper cost given that Centurios are easier to gain. I would say that 800 Centurios for any ONE Manifesto (Alexander Gear) or Datalog (Omega Gear) would be fair. A single chest piece or weapon from either of these 2 whole set collections would cost you 6400 centurios, which of course means a player would have to collect the Manifestos or Datalogs over time, given players can only hold 4000 Centurios at once. This means the barrier to entry is high enough that players will still be tempted to keep (or start) doing Raids on Savage as a means of getting all the gear pieces they want as quickly as possible, combined with buying some of the Books with Centurios.
It would still be nice if Square could come up with something to cycle-spend Sacks Of Nuts on however (perhaps a couple of new types of soil and seeds native to The First, for gardening? market prohibited obviously)