I don't think they've said "no" to Disney sequels, it's just that there hasn't been a recent film that's been huge enough to warrant one. But it's fun to see Eric on first name terms with Disney brass, and reporting back what he's obviously overheard in personal meetings between them.
Discounting the DTVs, which weren't really anything to do with Lasseter anyway (he just put a decent argument in to nix 'em based on them devaluing the original films), I expect Lasseter would OK a sequel to any Disney film as long as it was warranted creatively or commercially.
The only recent one that I could see getting a follow-up in story terms would be Bolt, and if that had been a bigger success, I bet we'd have heard about a Bolt 2 by now. But most films have their stories wrapped in in their single movies (Tangled). If there are places for them to go (Toy Stories, Cars) and the potential financial returns are healthy, they'll make those films, Disney, Pixar or otherwise.
At the end of the day, it's all about the money. If something hits big enough, you can always be guaranteed of more. I don't agree with the Monsters sequel, since as a prequel I think it throws away the basic concept and there was much that could have been played out as a continuation, but the first one made money and so we'll get a second.
And, as said again before, Pixar's upcoming bigger ambitions means they need a safety blanket in terms of bottom line. In case John Carter isn't a usual Pixar smash, their bottom line won't be hurt too much as they have the inevitable success of Cars 2 to fall back on. It's when Pixar's bottom line thins out too much that Disney will exert more creative control. At the moment, Lasseter is picking his projects carefully and protecting those interests.
But that by no means implies they won't make a Disney sequel: it just needs to have a big enough hit to warrant spending out on a second film, and they just haven't had they yet. Successful as Tangled has been, that will probably translate not into an actual "sequel" but in spin-offs and (hopefully) some more-of-the-same fairytale films.