Fans that want this game to fail, I question how much they actually care about the series.
A lot of the comments like "I am so happy that this piece of crap has been rightfully flushed" certainly come off as very mean-spirited and vindictive in tone, but let's be fair, most of the people I wager, are actually looking forward to, and loudly want, FFXV. The relatively low opening sales of LR would seem to suggest to them a hopeful relief of Square-Enix taking this to heart, and moving on - preferably in another direction - to something more favourable to them. I think it's quite clear that they still largely do care about the series, but the FFXIII games simply don't accommodate this vision.
Of course, this does mean a ton of people immediately dismissing LR as a piece of turd without having played a minute of it and - I suspect a good number on GAF who have never previously posted regularly in LR-related threads, but happily chimed in to the schadenfreude thread - perhaps don't know much about it besides Lightning and the fact that Toriyama is once again behind it. Yes, it seems unfair, even to me, as someone who recently did climb down a bit from that soapbox and willing to be more open-minded and willing to give something a try, but I suppose that's just the strength of Lightning as the symbol of an unfavourable press towards the first game coupled with seeing the series dragged out into three games with the next installment still so distant.
Furthermore, with such drastic first-week drops from FFXIII-2 onwards, I wonder how this will affect Square's decision to handle the FFXV "Epic" sequels. I suppose this can depend largely on how FFXV itself is received, and remembered, so it will be an opportunity to see whether that will have a decisive effect, or whether FF fans are simply growing fed up with direct sequels.
EDIT#1: Having said most of that, I'm not too sure why there is a need to celebrate it. Sure, someone may hate FFXIII and Lightning and can't wait for FFXV, but it's not like there's going to be a fourth game. Perhaps if Square was daft enough to consider a fourth FFXIII game, but they've clearly ended it, so...eh, I dunno. Schadenfreude can be weird...
EDIT #2: ...aside from laughing at how SE's got what they deserved. But what has SE visibly got out this? A probable modest profit given the small budget of the game, and Toriyama essentially getting his way in finishing the story? Lost goodwill in the company? But people still want FFXV. Guiz, what are we celebrating about, exactly?