It is possible that eBay is still experimenting with different messages in those slots, but my suspicion is that eBay already has vast amounts of data about how each possible message affects sales in various categories or even for each individual item or individual buyer, and eBay has incentive to pick whichever messages correspond to the maximum amount of sales according to eBay's calculations.
eBay may very well have good reason to think that the ideal use of this space in your listing is the following:
Other users may see different messages. If a user has purchased from you before, that fact is likely to be noted there. From a different seller's listing:
The number of watchers may be more critical for a rare or one-of-a-kind item that is listed as an auction to signal potential competition in bidding.
For commodity items where thousands have been sold and quantity available is adjusted multiple times per day as each sale occurs (as I assume is the case here), the number of watchers, even if it is in the thousands, may not play as much of a role in most buyers' decisions to make a purchase as you think. Why should a potential buyer care if thousands of other users have your item on a watch list, if there is little or no risk that you will be out of stock for an extended period?
In any case, eBay does not share its thoughts or reasoning on such matters; users are left to observe what eBay does and draw their own conclusions about what it means.
