Remember Dashie's fear of failure and sometimes overbearing self-glorification? I think the real meat of this episode was written between the lines.
I'd say timing is important and that managing to get along better with her parents could only happen right now, in this episode, not sooner.
I think this only makes sense if we assume that indeed Dashie enjoyed her parents' praise, despite the embarassment. That would make her an odd personality though, because I haven't heard something like this happening. Could be almost schizophrenic. Again - Would explain some of the other troubles she had to deal with and her current personality.

I would say the overall lesson of the episode was that if your parents are like that... be cool.

(Dashie tends to pretend to be cool, but underneath it might look different, which underlines this.)
Remember that this is not primarily a show to teach parents (although it hopefully does teach anybody), but to teach kids, so it doesn't matter whether her parents were a bad example or not. This was about how to deal with it.

As for the details: The door was a hilarious idea. (Subverting viewer's expectations is always fun.) Scootaloo's reaction to Dashie's outburst seemed overly dramatically extreme. The nap joke was the lowest point of the episode; horribly forced.