drop more ilv coffers in max level dungeons?

[Gemina]

For current dungeons, probably not. They want you on the treadmill.

For older dungeons, it absolutely should become a thing once the next major expansion is released and the old endgame dungeons become part of the levelling process.

You still likely need multiple runs to collect what you're after, and it would be such a boon to glamour collectors to be able to reliably collect gear pieces.

How about once the dungeon leaves the expert roulette? I think not having guaranteed drops for the two newest dungeons is reasonable. I am definitely ok with multiple runs so long as I know progress was made, rather than each one being a crap shoot.