That doesn't help to prevent the problem for grouping if you haven't run the quest before. If I'm reading you right, the vet can't run an previously un-run quest on hard or normal because they lose out on a 70% bonus that they can never get back. (If that's what "+70% for an elite completion your first time in a quest" means.)
I see no advantage for this kind of change.
I think the point is losing bonus XP on just one quest isn't nearly as bad as also losing it on the next four quests you run to build your streak back up. Sure, the vets & TR junkies will still want to Elite-streak the whole way, but there would be less of a disincentive to run a first-time quest on N/H.
Semi-retired Build Engineer. Everything was better back in our day. Get off my lawn.
Essentially I am ripping the hard/elite streak system out of the game and feeling good about it.
Then I'm replacing it with additional xp for first-time quest completions on elite.
You could do the same thing for hard to emulate the xp of a hard streak.
Also, there is a difference between 1st time bonuses on a difficulty and 1st time bonuses in a quest. It's in the quest XP report.
Changing nothing else in the system, you would still get 1st time completion bonuses on elite, hard, and normal (or casual) for any quest.
I'm trying to remove the psychological baggage of breaking a big streak and some of its side effects by removing the streak itself but keeping the xp you would get.
This would make it (I would hope) a little more bearable to run a quest or two with a friend or guildy at a different pace at a different difficulty (you know, just for fun, maybe) then go back to your regular questing routine without "losing" xp on further elite completions. This has essentially the same effect as most of the various "suspend the streak" suggestions that frequently come up.
The other advantage is that you can more realistically complete certain chains like harbinger of madness.
Complete the first 3 quests on elite, then In the Flesh on hard.
Full xp bonuses for the first 3 quests just like now.
Xp bonus for a first-time hard completion for In the Flesh.
Then when you go to the next quests (Lords of dust maybe) on elite, you are back to your full elite bonus again without having to build up a streak.
Should you return to In the Flesh later and complete on elite, you would still get a +80% first-time elite completion, just like now. But yes, you have missed out on the +70% first-time quest completion. You would have gotten a smaller bonus instead, like 35% for hard, same as it would be now with a bravery bonus. I feel quite a lot of people would find this compromise just fine for a quest like In the Flesh, though.
There is no advantage to anyone who would not consider to run something at a non-elite difficulty first time. There is also no disadvantage.
There are quite a few advantages to everyone else.