Perhaps I misunderstood what the OP had an issue with. I perceived it as, when you attempt to run an application from a large, collective menu of all applications, if an instance is running, it would go to that instance, instead of starting a new one. This is not the way it is in Windows.*
If the OP declared that clicking a running application opened the running application, then yes, that has been the way it is for a while now, but it was that way in Gnome2, so I suspect this is not the case.
If the OP declared that clicking a running application opened the running application, then yes, that has been the way it is for a while now, but it was that way in Gnome2, so I suspect this is not the case.
* added this sentence in edit.