Release a 16 person 4 hour long dungeon

[Richard_BG]

You know, the main reason instanced dungeons are timed are so that no single group of players hijacks the dungeon for themselves.
There are only so many instances that the server can handle due to memory issues (look at one of Yoshi's posts in Rein's translation thread, no matter how good they make the servers there WILL be a limit), and if the dungeon is timeless, at some point in time some obstinate players will just stick to the goddamn dungeon until they're done with it, or otherwise a group of usual forumgoers decides that it'd be a great thing to lock everyone out of said instance by occupying all of it's slots.
So there are essentially time limits so that people WILL be booted out of them to give others a chance.

# of instances is only limited by their horrible servers. 2.0 changes this and so your thoughts on instance hogs will be mute. This is also not the main reason dungeons are timed. They are centered around the Time Attack principal and players are rewarded for completing it speedily. That is how SE intended them to be.