You have misunderstood your Wikipedia excerpt. What the excerpt is saying is that in some areas, "gaming" is distinct from gambling in that "gaming" is something which is legally-approved. That is to say, "gambling" may or may not be legal, but "gaming" is. The article suggests that this distinction is not universally recognized, and I agree with that -- I sure as hell never thought of the word "gaming" as suggesting legality one way or another. The example provided for the UK shows that "gambling" may also refer to legal activity as well. This does not in any way suggest that they do not recognize "gaming" as a synonym, nor does the article suggest that it does. Indeed, the UK has a number of legal recognitions of "gaming" as referring to gambling -- for example, in 1960, the "Betting and Gaming" act legalized Bingo in the United Kingdom. This helped weaken a move away from gaming in the UK -- for example, parliament's Gaming Act of 1845 held that wagers were not enforceable contracts.
So, yes, the UK does use "gaming" in the same sense, and that sense goes back for literally hundreds of years. While "gambling" can be used in place (and since we usually discuss "gaming" in the sense of video games, I actually think that's appropriate here), it is by no means incorrect or unreasonably pro-industry to use the word "gaming." It literally means, according to the dictionary, "the practice of gambling." It has been used in this context for centuries. That is why people continue to use it. Because that's what the word means, has meant for a very long time, and that is the word which is used most frequently by people who discuss it regularly.