I don't think the elves should simply forget or ignore their past, but I think a big adjustment is in order. Playing as an elf inquisitor who started the game as a devout believer in the elven gods, I'd say my character's view (and mine, to be honest) as of Trespasser is that the elves need to know the truth of their history. All of it--that is to say, everything that can be proven now, and everything that has been presented and may or may not be true, all with full acknowledgment of how much they still don't know. My own Lavellan, if given the chance, would speak to as many of her fellow elves as possible and tell them everything she's learned. Further, she would urge the elven people to continue to try to learn more about their own history, but not with the aim of restoring it in the present day. Rather, she now feels that they must learn their history in order to avoid repeating the mistakes of their ancestors, because she really doesn't think the world of the ancient elves deserves to be restored.
If the Dalish want to repurpose some of their old traditions and give them new meanings, that's fine, as long as they know who their ancestors were and where they went wrong. Learn from them, but don't worship them. And they definitely do need to find their own way forward and create their own identity based on who they want to be, not merely who they (erroneously) believe they used to be. After all, we all know what they say about those who forget history.
Wow. Every single line of your post. Me likes. Too bad I cant give you a "double or triple likes", but here, have hearts instead

My Dalish quizzy cant help but feel that she now stands in similiar shoes as Dorian's. The truth needs to come out, rectify their mistaken lore and look better for the future instead of wallowing in the past that they got completely wrong anyway.
But she knew that most of her People would be too stubborn to learn nor do they have the proper humility to accept that they were wrong: times of Elvhenan aren't THAT great after all. And the bitter and ugly possibility that the Tevinters may have caught their bad habits from (most of) the Evanuris, mages so powerful that they demand to be treated like gods.
Even if somehow they could be brought to see the truth for what it is, she fears that they would still have difficulties in having a change of heart.
She realizes painfully that she might have to do what Dorian has done: slay their own countrymen because those people forces their hand.
And the most painful part of all? She's married to a Human. Divine Victoria and a Tevinter Altus are her Best Buddies of All Times and those things could be used as an amunnition from the opposing side to say that this Lavellan cannot be trusted and being seen as a human tool. While she earnestly strive for her People's well being while trying her best in keeping the peace as well.
She wants Elvhen glory too, but having to achieve that with hard work and patience (using Wycome as template. Bless Varric for his kind soul!) And not through chaos that will result the destruction of many others.