I think there a room for a lot of improvement on the current system, but your suggestion is... frankly just bad.

Once you have geared up your main, and either can't get better gear, or it's greatly slowed down because you have all the weathered gear or something... then you would many times want to gear up an alt job, but with your system, you would already have all your jobs geared up... Pretty boring IMO.

I'm a guy that usually just focus on one job, but even then, I would hate this... I don't want to gear up my main, only to never get past my alts, who have the same level of armor....