Old timers may remember three previous programs, the last one being the very popular AdCommerce which was closed four years ago. It was a real money maker for sellers, not so much for eBay!
I have not been invited either. I suspect they are inviting American sellers exclusively... as usual.
I loved everyone of the three previous programs. The last one (AdCommerce) was the best.
My average monthly cost would be a bit over US$50 while generating additional sales of over US$1,000. It could be customized to target the buyers you wanted in their own country. With my eBay sales at the time in the $10,000 to $15,000 range monthly, it was a nice addition at a very low cost.
Keep in mind that a buyer, once obtained, often keeps on coming back regularly for years. So it was not only $1,000+ additional monthly sales, it was also the extra sales that would be generated by those newly attracted buyers (many of whom also became regular customers on my website) for years to come. 
"we should not have to pay for our Stores fees anymore"
You do not need to pay for a store. It is a choice some sellers make to have a store, generally because they save money on listing fees and FVF.
I think most sellers today recognize that they pay eBay much less than five or ten or fifteen years ago for listing their products on eBay. And I mean MUCH LESS.
The difference is that FVF have generally increased to make up for the overall reduction in listing fees.
"why eBay still needs featured listings promotions when it claims that its search engine pulls up the most relevant items "
These advertising programs have nothing to do with search results.
They are additional paid advertisements
Today, if I go to eBay.com and do a search for antique pattern for blouse, I get:
In addition to the listings offered by eBay sellers, I see paid advertisements by a car company (left panel), a cable company at the bottom, advertisements paid for through AdChoice (you may see different advertisers as they rotate)
What eBay used to offer was similar: sellers would pay extra to have their advertisements (including links to listings or store home page) show up - instead of a car or whatever.
Considering that eBay needs and wants the extra advertising revenue, It does make a lot of sense to me to allow eBay sellers to show their wares instead of outsiders.
"The reality is that eBay's search is far from perfect to begin with"
We all agree to that - more so if you are a Canadian seller.
But those paid advertisement programs have nothing to do with search.
Back in the days when I used AdCommerce (2008-2010), I seldom used the advertisements to show a specific product or listing.
I was selling and promoting my name ("name recognition" is the most important part of marketing), my store, or a group of products on sale. Never had anything to do with search results.
"if search is supposed to be perfect, a seller with a valid sales model should be able to sell virtually at will up to logistical limits and wouldn't need advertising"
You lost me.
Let's assume the search is perfect.
50 sellers list an item that offers all the criteria to be on top of the search result page. The 50 sellers are all TRS-Plus, offer return with refund, ship within one day, offer PayPal, all have 5.0 DSR across the board and 100% feedback. Since the search also looks into buyer's patterns, all potential buyers fit in.
Yet, even with a perfect search only one will be on top, one will be second, one will be third, etc....
I think sellers expect too much from search. They cannot all have their listings on top or near the top of the search or even on the first page. When a search result page offers hundreds or thousands of listings, somebody will be on page 2, on page 4, etc...
Paid advertising promoting your name or your store has nothing to do with search results. It is a different method to attract buyers.
I understand that you and millions of other sellers do not want to pay more money to advertise on eBay. That's fine. However, the program is for those willing to spend more to attract buyers.
