What were all you guys' reactions when you first heard Brawl was coming out, before you knew exactly what it was going to be like? It was likely a feeling of genuine excitement, a "Wow, where can they take us now?" feeling. I doubt anyone back then was thinking "hah, replacing Melee? NO WAY".
We only feel that way now because we're disappointed by how Brawl turned out. But if we're going to let that disappointment color all of our impressions of future attempts to make "the next Melee", then we're allowing Brawl to hurt Melee's legacy much moreso. Opinions like "hah I'll never drop Melee" arise from disappointment at Brawl, but really, if we dislike Brawl so much, why are we letting it affect our opinions of Project M?
As for it being a hack, well, I remember before people said that we couldn't use Brawl's custom stage feature to make our own tournament stages because that data is on SD card. If I'm not wrong, the Midwest Brawl Circuit is currently running tournaments with custom stages... Things change, and there's no reason to dismiss it just because it requires an SD card to play. With the advent of StackSmash, you don't even need to mod your Wii to play Project: Melee, or any other versions such as Balanced Brawl, Brawl-, Brawl+.