Mrebo said:

Because such flaws can be found in all the OT and because there is so much greatness in RoTJ. In ANH, Luke defended Obi Wan as a great man against Solo's disparagement. What did Obi Wan do that was so great in the day or two that Luke knew him? Acted nonchalantly after Luke's family was killed? How about when they all jumped into the garbage chute and the Imperials would have easily figured out where they were but sort of disappeared for awhile? How about Alderaan's destruction barely mentioned again? How about how quickly they trusted Lando at the end after he sold them out?

Heh, awesome! Interestingly enough, all of those had crossed my (subconscious) mind, but were never present at the surface.

With the first few, I'd say that it fits Luke's character to be wide-eyed and naive and quickly find trust to his newfound pleasant "mentor" (look how he gets, well, a bit butthurt when Solo disbelieves in the Force, even though Luke never saw a demonstration of it), and it fits Obi-Wan's character to be calm and consoling - probably realizes the grief and doesn't want to annoy him with long speeches.

If anyone is too nonchalant about their death, it'd be Luke. He also doesn't care too much about the death of his friends in the dogfight, it seems, and Alderaan doesn't get mentioned, but all of these are sort of excusable by the fact that the characters have shit to do almost all the time until the end.
Probably started grieving after the parade... or inbetween.

With the garbage shaft, I've always thought the Imperials had launched the death trap to kill the rebels inside, instead of jumping down with them... could've thrown a bomb, though.

But yea :)