It's a critical turning point in any campaign when a side-quest, whose only importance is in enabling the main quest to continue, assumes such an aura of necessity that the objects of the main quest become irrelevant in the minds of the players.

It's a second critical turning point when a side-side-quest assumes such an aura of importance that the objects of the side-quest also begin to pale into insignificance.

Transcript

Qui-Gon: Hey, Obi-Wan—
Obi-Wan: I'm back at the ship, remember.
Qui-Gon: HEY, OBI-WAN—
GM: You can't shout... oh, for crying out loud. You've got a radio.
Qui-Gon: Cool! HEY OBI-WAN—
GM: You don't. Need. To. Shout.
Qui-Gon: We need a lot of money. Can you Appraise the Queen's wardrobe?
Obi-Wan: I don't think so.
Qui-Gon: Yeah, I didn't take any points in Appraise either.
Obi-Wan: Actually, I did, but the clothes aren't worth enough. Even the ship would barely pay for the weapons we want.
Qui-Gon: Great idea! We can sell the ship to get the weapons!
R2-D2: I see no flaw in that plan.