The problem with the latest Kies 188.8.131.5271_128 not having the Samsung Apps store is as a result of either a corrupt "AStorePlugin.dll" or a wrong value assigned to this dll. The problem is only with the "AStorePlugin.dll".
To solve this problem, simply install the latest kies (either as a fresh install or an update over existing kies instalation. Restart PC.
1. Now go to Program Files\SAMSUNG\Kies\Plugins\AStore...
(a) inside the AStore folder, replace the "AStorePlugin.dll" with the one from the download link below (or from any previous kies installation)
NOTE: ONLY REPLACE the "AStorePlugin.dll" of size approx 4,014kb.
(Don't replace the small one of size about 4kb).
3. That's all. Now you can enjoy your new Kies 184.108.40.20671_128.