Lithium metal batteries are better candidates for primary batteries (or aluminum metal, or sodium metal) and already exist in some forms commercially. I assume you're talking about applications where very high energy density is needed, like consumer electronics. The issue is that lithium is becoming a concern from the supply side, so while it is still relatively cheap, nobody really wants to make primary batteries out of it when cost increases could destroy the business case by the time the production facility is built. Also, recyclability is an important factor - maybe Li-S is better than Li-ion in terms of energy density and potential for development, but from all I've seen it has no clear edge on Li metal batteries for any application except for its ability to be recharged. For other applications where primary batteries are acceptable and mass and volume are less of a concern, aluminum or sodium metal batteries are almost certainly more cost-effective, and definitely easier to make a case for scaling.

Thank you for the comment.

And me also, have been searching

about Li/S batteries as primary battery.

and there was a critical flaw.

A self discharge rate of Li/S batteries is 15%/month..

i think this explains pretty much...

 Mr Britton is right, Li-S battery have already existed in some forms commercially. But another problem is that Li metal is not stable, it has security issues. Indeed, many researchers are working on this problem.

A primary lithium-sulfur battery can be built and used because sulfur is in the insoluble form when you start.  However, once you start discharging the battery, the sulfur becomes soluble polysulfides and self-discharge happens.  Therefore, if you start using the primary battery, you must use it all right away  or else it will discharge itself. However, with a membrane that we worked on recently, we are able to stop this process. Read here: http://jes.ecsdl.org/content/164/4/A560.short