How does it kill career mode? Unless you are starting a new career mode every week, the ratings don't carry over to it. Career mode is about developing youth, etc. Whether Monreal is 80 or 82 rated is no big deal.
If you want you can always edit the ratings yourself before you start a career mode.
Auba is already highly rated. He shouldn't be upgraded for playing as expected.
Monreal maybe you have a point there.
Your points about Chelsea and Man U are hyperbole.
Ultimately, Arsenal is a 6th place EPL team. If certain players get upgraded, then certain others should definitely be downgraded to make up the difference.