Whenever I hear about ancient cultures, especially those from the Neolithic through the Bronze Age there are always a hodge-podge of different naming styles. On one hand you can talk about the Minoans or the Hittites or the Sumerians, but on the other hand many cultures, some important or influential have rather uninspired, clearly descriptive names like the Bactria-Margiana Agricultural Complex or the Neolithic Funnelbeaker culture.
I know that the naming practice is generally to name newly discovered cultures after the first site that they were found at. The obvious answer is that historical cultures are identified by what they called themselves when we know that information, but that does not explain how the ancient Cretans who's language we cannot read are Minoans rather than something like "Knossos Palatial Culture" or why archaeologists talk about the Villanova Culture when they were infact early Etruscans.
I know this is a really long set up for the question, so why do some ancient cultures discovered by archaeologists have "their own" names and some are simply named for where they were first found or given some purely descriptive names? Is it essentially arbitrary based on when and where they were discovered? Or is there a system for identifying newly discovered cultures with names from the historical record? Or does it depend on the context that you are talking about each culture in?
There are a lot of very different reasons why ancient cultures get names from scholars. I think the main difference in what sort of name they get is whether they are remembered in writing or not. Minoans, Hittites, Sumerians, Assyrians, etc. all have references to them as a sociopolitical entity in written works from other cultures. Basically, we knew they existed before we excavated them, and we have stories that refer to them, so we use an Anglicized version of that name (Minoans named after King Minos, Assyrians named after their capital city of Aššur, etc).
However, before the advent of writing, we have little idea of exactly what defines any given group of people. We don't have any descriptions of them, we don't have an idea of political organization, we don't have any ideas about their self-identification or external identification, so we have to differentiate them the only way we know how, by their material culture. This doesn't always tell us about political organization. The Beaker culture may have had lots of tribes running through Europe that all used the same sort of artifacts, but were politically distinct. We can't tell, because we have no writing. So we find that this set of people used similar artifacts for s certain time period, and since that's how we define them as a people, we name the set of artifacts they use and we use that as a definition for the people group when we talk about them as a whole, since it's the only way we have of defining them.
This generalization is usually only used when talking about large-scale trends and processes. Most of the time when dealing with details, archaeologists will use archaeological sites and even specific levels within those sites as identifications for people. Such as Troy VI (the 6th city of Troy, excavated by Heinrich Schliemann, considered to be the city involved in the conflict later embellished by Homer as the Trojan War), or Megiddo V, or Kebara Cave, or Ashkelon Phase 20a (the first Philistine occupation in Israel). Of course, there are names for the people groups or cultures associated with these sites, but typically scholars studying these sites in comparison with others will attempt to be as detailed as possible, to avoid conflating groups which may share a certain amount of material culture, but who never interacted and may have been politically distinct.