Neat trick. I ask a question which you answer thus:
Does it matter? The point is not those.
And then having evaded any kind of real answer, in the next sentence you turn around and ask me the very same question in different words:
If you were forced to create attributes that were not the Big Six (or the Big Six renamed), what attributes would you create or use? (So no "they are perfect as they" are non-answers.)
Hmmm...
There's certain aspects of a character - particularly the physical ones - that kinda need to be mechanically represented somehow: raw muscle power, endurance, short-term (sprint) and long-term (marathon) stamina, body agility or co-ordination (seen in things like dancing, gymnastics, etc.), manual dexterity (fiddly use of hands, feet, etc.), and appearance/attractiveness are but some. D&D covers these with Str Con Dex and a part of Cha, but it's clunky.
Then there's the non-physical aspects of a character, mechanical representation of at least some of which also comes in handy: willpower, learning comprehension, info retention, memory capacity and-or accuracy, cognitive processing (the ability to get C out of A plus B), spiritual fortitude (or, resiliency of the soul), judgment, and - for lack of a better word - radiance. D&D has Int, Wis and some of Cha for these; again vaguely functional but clunky.
So, that's about 15 "attributes" - 7 physical and 8 non-physical - which is probably too many to be viable. A few can easily be conjoined; for example learning comprehension, info retention and memory can be concatenated to two: learning prowess and memory. But you're still going to end up with twelve or so:
Strength: raw muscle power, carrying capacity, bench press
Short-term stamina: how well you stand up under short bursts of high exertion e.g. a sprint or short martial combat
Long-term stamina: how well you stand up to prolonged exertion e.g. a marathon or a lengthy climb (also plays into disease and poison resistance)
Endurance: how much abuse or pain can your body handle before it gives out; also how fragile are your bones, joints, etc.
Co-ordination: how clumsy or dextrous are you (this could be broken down into full-body and small-scale co-ordination if desired, I've combined them here)
Appearance: how physically attractive and-or sexy are you, includes body build/type as well as face
Comprehension: how well and how fast do you learn new things, also how quickly do you re-learn things once known but forgotten
Memory: how well do you remember things, and for how long, and with what accuracy
Cognitive processing: how good are you at synthesizing information, solving problems, reaching conclusions from data or evidence given, finding patterns or trends
Willpower: how determined (or stubborn!) are you, also a measure of mental resistance to influence
Spiritual fortitude: how strong and-or resilient is your soul or spirit (highly relevant (but often overlooked) in games where revival from the dead and-or spiritual travel may occur)
Radiance: how much personal magnetism do you exude, also how persuasive or captivating are you
I intentionally left out judgment as this would normally be reflected in a characters role-played personality rather than mechanical stats.
Very conveniently, there's now 12 instead of 6. Intentional? Not really, but I like that it worked out that way. Even better is they remain evenly divided between physical and non-physical - 6 each - though I'm very open to re-jigging of the physical ones. How these would be rolled up during character generation is a topic best left for another time...
And note the above names are more intened for clarity than in-game use; better ones can be found for about half of them.
So, I've given my attempt at an answer - how 'bout you?
Lanefan