You are thinking the wrong way. There has been mastery resets given to people when there was a HUGE balance update. If your combinations was not viable no more you would be granted one.
You can say that people knew that advanced would come but it has been promised for years and from what Rory said recently, there won't be advanced for a year or two. Therefore, like you brought up gameplay, you can't expect someone will limit his gameplay by playing solo fire or solo medic for years for something that has no ETAs.
Some people has been elemental/medic for years and you can't pick and choose who's worthy of one. There is some people that loves int medic, you can't ask them to play this mastery for a year or two straight, it has 3 offensive jutsus
I, myself was an elemental medic and decided to reset for advanced TWICE and regreted... because they won't be coming for a year or two now...
Regardless of how you play, it is unfair to ''punish'' someone for something that has been teased for 2 years and that won't be coming for at least a year.
In my honest opinion, it just seems malicious to wish others should get punished and have to reset to do 60-70 levels on multiple chars for this.