The provenance of a given coin, token or medal not only affects the market price, it has other functions. Perhaps more importantly tickets give us a hard copy trail that should be protected, in many cases a short hand to a pedigree, ideally but not always, a chronological trail. Often, even with the advent of tickets a complex international provenance which jumps centuries can be difficult to bridge, let alone without them.
BNS Research Blog 
I agree wholeheartedly with Chris Tyrimos’s comments regarding coin tickets and how important they are.
I also feel that encapsulation has a lot to answer for. Apart from the loss of coin tickets, this process also fails to record the weight of a coin, another extremely important aspect of most coins.
Recently I sold some coins through a well known reputable coin auctioneer. They decided to encapsulate some of the coins. Later when I asked what had happened to the tickets I was told they had been thrown away! I could not believe it.
At last someone who feels the same way about tickets as I do. Well done. I recently sold my 1887 collection and offered tickets, catalogues and invoices. Many of the coins with uninterrupted provenance back to Murdock. Apparently buyers are not interested in the original invoices or the catalogues and you are right to point out that slabbed coins very seldom are sold with the original tickets. More is the pity. Collectors tend to keep the information more than the slab it and sell it investors. It is the same with original cases. Numismaticly it is very important to keep sets together with their cases as this shows so much about the development and struggles within The Royal Mint. This is particularly so with 1887.
Yes, indeed, to the comments above and the argument of the article linked. It’s a shame anytime the connection is lost between a coin and its tags (or invoices etc.). That’s why it’s worth showing people how provenance plays a part in every aspect of numismatics, and why the tags also must be conserved as artifacts in their own right.
More recording and sharing of them can only be a good thing. Now, I am hoping the “coin tickets” file will eventually expand to cover more ancient collectors!