Hey guys,
Here's a suggestion to have BG fans love BG3. And I'm actually going to suggest something coming from (GASP) Dragon Age Inquisition.
Why don't you allow the possibility to import a BG2 save file into BG3 to carry over some of the narrative choices? For example, if the BG2 protagonist was a half-orc mage. It would be great if there would be some dialogue or other text referencing this in BG3. It could be really simple fluff like this that would really make the BG1/2 fans go "Wow, they thought of this x detail from my beloved game". I honestly wouldn't even go overboard with this (Locking content behind a save import file or other crazy things like that), as it's really all about evoking nostalgia.
And if it's not possible to import a BG2 save file, the tapestry option from DA Inquisition to import choices from BG2 could also really work. Even if it's a smaller more redundant version of it.
I think many of the negative impressions so far have been really about wanting and deliberately searching for that sense of nostalgia. Feeling like coming back home. Providing an import save file feature would directly address this.
I don't think that is possible due to the different engines in which the games were made. But listing choices from BG2 during character creation is viable.