For standards to be standards, you need to have precise definitions, limits or rules that are widely accepted so they become the minimun acceptable benchmark. For example: From a reviewer's POV, they seem to agree that bugs are undesirable. But do they agree on how bugs and their severity impact a game as a whole and to what degree they detract from it to reach a final score?
So, unless they can reach consensus on exactly what they'll be taking into consideration and where they put the thresholds, those standards become personal standards. And personal standards are preferences that messured and expressed by each individual reviewer then become opinions. Informed, qualified, educated, etc...but still opinions.
OTOH, having an empire build or a "good" tactical combat are features that not every good TBS game need to have. Furthermore, you can have many of those features in a TBS, but if they don't integrate well with each other and the whole, they become obstacles that diminish the quality of the game.