Why not allow class changing during duty finder dungeons?

[Naunet]

Class lock was implemented to prevent us from running 6blms+1healer+1tank and then changing later on in the dungeon to something else. I miss this feature from 1.xx, but it makes sense and added balance to the game.

In what 8 man encounter is this actually prevented? 99% of them don't have any trash. Even in Coil, when you go from boss to boss, you're shunted to some strange, positionless lobby room between each boss where you can change classes. It's a bit silly.