Set counts are not 1/1 because part of testing who is the better player is testing who is better for a period of time longer than 1 game. Otherwise we could just do friendlies, chip in $5, round robin 1/1 each other and call it a day for whoever has the best record. Skill is more accurately defined and acknowledged over multiple games.
Doing CP's first does not lead to a stable series of MU's, it leads to more RPS CP scenarios. If starters are believed to give the average cast member the best hope for finding a neutral playing field against most other cast members, it does not make sense to push this off towards the end of a set. Finding out who is the better player will best be served by not encouraging more CPing than the current format imo: if you were to pose the question of playing exclusively on starters vs exclusively on CP's, starters would likely win for finding more skilled and less imbalanced gameplay from the cast.
It also breaks from the traditional mold by not allowing a loser to retry CP. If a person fails his CP in this format at any point except for Game 1 sorta, he's put into more pressure that before since he lost the right to stage pick. A person who won the coin flip to CP first, in a 3/5 set, can have the opportunity to pick twice before his opponent has won on any stage. When this double pick situation is ALSO tied to something essentially like a coin flip or RPS at the beginning, it doesn't portray a more fair start than doing stage striking for Game 1. "Sorry I lost the coin flip, guess you get to pick the stage first during the most crucial part of the set (You get to pick stage first + this first CP is done prior to any losses in the set so it's not really an earned advantage).
If we have an issue with current format, then regulate the importance and impact of CP stages by limiting them, changing them, banning them, whatever. Changing the format to try and minimize the impact of CP stages, by that suggestion, impacts the relative neutrality of Game 1 and tries to push that neutrality to the very last possible moment.
TL:DR
Game 1 in the current format undergoes a much more fair process: nobody gets a direct stage pick, nobody gets to choose from CP stages, both players basically have equal weight on what happens. This is one of the best things to happen to Smash, and changing it to fix other potential issues in the stage selection process seems like the wrong way about fixing other problems.
Doing CP's first does not lead to a stable series of MU's, it leads to more RPS CP scenarios. If starters are believed to give the average cast member the best hope for finding a neutral playing field against most other cast members, it does not make sense to push this off towards the end of a set. Finding out who is the better player will best be served by not encouraging more CPing than the current format imo: if you were to pose the question of playing exclusively on starters vs exclusively on CP's, starters would likely win for finding more skilled and less imbalanced gameplay from the cast.
It also breaks from the traditional mold by not allowing a loser to retry CP. If a person fails his CP in this format at any point except for Game 1 sorta, he's put into more pressure that before since he lost the right to stage pick. A person who won the coin flip to CP first, in a 3/5 set, can have the opportunity to pick twice before his opponent has won on any stage. When this double pick situation is ALSO tied to something essentially like a coin flip or RPS at the beginning, it doesn't portray a more fair start than doing stage striking for Game 1. "Sorry I lost the coin flip, guess you get to pick the stage first during the most crucial part of the set (You get to pick stage first + this first CP is done prior to any losses in the set so it's not really an earned advantage).
If we have an issue with current format, then regulate the importance and impact of CP stages by limiting them, changing them, banning them, whatever. Changing the format to try and minimize the impact of CP stages, by that suggestion, impacts the relative neutrality of Game 1 and tries to push that neutrality to the very last possible moment.
TL:DR
Game 1 in the current format undergoes a much more fair process: nobody gets a direct stage pick, nobody gets to choose from CP stages, both players basically have equal weight on what happens. This is one of the best things to happen to Smash, and changing it to fix other potential issues in the stage selection process seems like the wrong way about fixing other problems.