...How many veteran players will show up at an engineer's base with mat's for a G5 mod', do a bunch of rolls, fail to get anything decent and then think "I guess I'll just apply a G4 mod' instead" rather than going back out and looking for more G5 mat's?
Me, for one.
There's much too much to do in ED, and since I'm not focussed on PvP, I can live with whatever mods I can get onto my ships.
Sure, I'd like to get G5 upgrades, and I'd like to get good G5 upgrades, but scouring the various locations for mats to do a hundred rolls so I can get a god rolled FSD or thrusters? Nope. Most I did was IIRC 20 mats for a DD5 roll, and none of them turned out god, so my combat ready (well, kind of) iCourier only boosts to 796 m/s, not over 800. Most of the time, my main issue with the mats is that I have to decide what to throw away - they just accumulate while doing everyday missions. Sometimes, I throw away the wrong stuff - e.g. when I realized that I could have used those useless Decoded Emission Data to unlock an Engineer. So what? It's annoying, sure, but that stuff accumulated without me doing that much to get it, so some more will come over time.
All in all, I'd have to say that from the presentation, I like the new Engineering - the crafting process itself is not that hot, but the combination with the mats brokers and the new inventory setup looks good. The way I see it, FD tried something with the old crafting system which didn't work out the way the game designer(s) wanted it to (god rolls), so they replaced it with something else. They kept some of the RNG aspects and removed others (penalties are now fixed). From what I could see in the livestream, a lot of thought went into this new concept (flame me...) - most critics here are focussing on the mechanics and the way that it may not be possible to reach the top 25% god rolls, nobody mentions the extended range of secondaries/special effects that were introduced and only hinted at during the livestream.
Yes, it's different.
It will be much more effort to grind your way to a fully god rolled ship, which from Sandro's words sounded like this might be somewhat intentional.
There seem to be many more possible combinations than there are now for secondary/special effects.
For people who don't want (or need) a fully god rolled ship, things look like they could be easier - mat brokers, guaranteed progress, guaranteed secondaries, workshops in the stations.
As for grandfathering - I wouldn't be surprised if, half a year after these changes go live, all the old modules will have disappeared because the new possible combinations have made them obsolete.