We have the bronze. We have the gold. We have the platinum...where's the silver?!?
With the it costs 100 Lounge Trinkets to buy. You get 50 Steamworks trinkets in return.
With the it costs 200 Lounge Trinkets and you get 100 Steamworks Trinkets in return.
With the it costs 500 Lounge Trinkets and you get 250 Steamworks Trinkets in return.
Why not have a Silver Bag of Steamworks Trinkets? It'd cost 150 Lounge Trinkets and you'd get 75 Steamworks Trinkets in return.
I feel rather off that it jumps right from Bronze to Gold without having Silver in the middle :P

We don't have one because it would look identical to the Platinum one.
I wonder why there is even a platinum one? Why not just bronze, silver and gold?
Seems pretty pointless to add another bag just because one isn't labelled silver. A 25 trinket difference isn't enough to justify creating another item, imo.
Because it gives the highest amount of Trinkets the Platinum :)

Because platinum doesn't tarnish, and makes better airships?
/rimshot xD
IDK. But I hadn't honestly noticed the difference - I guess I don't care either way as long as there's a decent choice of currency trade ins. I don't mind if it stays the way it is right now, unless there's some hugely pressing need for a 150 trinket trade in amount.