Speaking as someone who spent his first thousand hours in-game as a strictly non-combat pilot, I can't say that I'm as keen on this notion as you are.
Not much impressed by the idea of those who for whatever reason (I had to train myself to use my rudder pedals as primary and secondary fire buttons to limit the stress on my somewhat fragile hands before I could do the pew-pew) don't engage in combat - and there are a fair number of them - being saddled with a second-rate material-gathering system.
I'm not saying we get rid of the current system - although I still think that should be made easier to find mats as discussed earlier in this thread.
But I just think it'd be a good idea to have a skill-based mechanism for farming the high level mats too.
And combat skills based makes the most sense as the main reason for engineering the ships is to make them better at combat. The main non-combat mod is FSD range increase and the G5 mat for that is encoded so wouldn't be covered by my suggestion anyway.
Most of the other non-combat mods are weight saving ones and I never hear anyone complaining they can't get the mats for those anyway.
At the end of the day I don't see a drawback of *adding* a skill-based G5 mat gathering method as long as it's not removing the other methods.
