There are objective measures to evaluate anything including art. But the experience you have with art is vastly different from everyone else because of who you are, your life experiences, your previous art experiences, etc.
"Objective" definitionally means it can't be shaped by personal taste, opinion or feeling. So to a certain extent, you can only "objectively" measure art in so far as you can state facts about it. Ultimately this comes down to the Is/Ought gap. You can't derive a statement about how something
SHOULD be from statements about how it
IS. Ought is inherently dependent on a subject with personal judgements, Is is not.
"Fallout New Vegas has a significant amount of bugs due to a limited timeframe" is a statement of fact
"It is bad that Fallout New Vegas has bugs" is a statement of personal judgement, since it is a claim of how something
SHOULD be, "New Vegas should not be like this", which is inherently requires a subject capable of reaching judgements. If there were no people but New Vegas still existed, nobody would be able to say that the bugs take away from the experience, since there would be no experience.
Now you might say "Well there are certain standards which human beings find aesthetically appealing" or "There are certain established norms that art follows", and even though I'd have my own criticisms of those ideas, even if we accept them as 100% true, that would still make art standards only
Intersubjective (I.E Subjective, but shared among people rather than being atomised and individualistic).
Since "Good" and "Bad" are judgements, and judgements necessarily need a judge to make them, they can't IMO be objective. Objectivity requires the facts to be exactly the same even if there are no humans around to measure them. Good and Bad can't exist without humans.
Without objectivity, how the hell do things get better? When it comes to games, how to things like cameras, combat system, overall movement and so on get better with time?
Because they feel better and more intuitive for the vast majority of people to use.
It still requires
People to see those combat and movement systems and say "Yeah this is easier to use than this one" or "The flow of this one feels much more intuitive".
If those things were objective, it would mean necessarily there would have to be no personal judgement involved whatsoever. Saying "The Combat System got better" is reliant on someone playing the game, and deciding it feels better to use.
Saying "This combat system works this way" would be objective, saying "It is therefore better" relies on it feeling better for people, and if it's reliant on how it feels to people, then definitionally it is Subjective as to whether it's getting better or not.
That said, as I've said above: if something's agreed upon by most subjects it's generally considered to be
Intersubjective as it's shared between people but still requires a person to come to that judgement.