First let me say that the recently release trailer has me extremely hyped up for not only 2.5, but the expansion as well!
That being said, after seeing the Keeper of the Lake dungeon, while it does look really fun and epic, I can't help but feel a little disappointed to see that it was 4player dungeon.
Coming in from 1.0 and seeing the demolished Imperial Airship I've always wanted to go there and thought it be some kind of epic alliance based content, or at the very least a solid 8 man dungeon. After finishing the 2.0 main story I kind of hoped that the raid would be similar to The Praetorium in terms of scale. (After all, this is Midgardsormr we're talking about! Even if this is just a lesser powered rendition of him, If he could take on the Agrius, surely it would take more than just 4 players to slay him. Hopefully we see him again in 3.0)
Maybe it's just me, but I've grown very tired of 4 player dungeons. They were a little challenging in 2.0 and 2.1 but only because back then you didn't really posses the gear/stats/ilvl which alleviated some of the risk. But, after a while they kind of just lost their allure and became a grindfest/timesink with very little appeal. I know there's coil, and I was in a static that did first and second coil, but my rl schedule has changed to the point where I can no longer commit to multiple tier progression raiding.
I miss 8 player dungeons like the ones in 1.0. The Old Cutter's Cry, Aurum Veil, and Dhzmeal Darkhold were moderately challenging ( especially with the gear available to first time challengers), they had unique puzzles in certain rooms that you actually had to think about in order to gain the full benefit of completing dungeon, and rewards that were inside actually made players want to do them. (Who said all your BiS gear has to be from Poetics or Coil. Maybe even the augmenters could come from these kinds of dungons as well; like what they did in the Syrcus Tower. )
I hope that when Heavensward hits that we see more Dungeons like this. Although my schedule forces me to play on a casual basis, I'm a player that likes to be challenged. I like to play with family and friends in big groups. I love the bonuses that playing in a big group offers. I hope that full parties going onward wont be limited to tier raids like Coil and Alexander or primal battles. I like the prospect of going into a dungeon and having the possibility of not being able to clear all the rooms and bosses on the first attempt; not because the group is bad but because you actually had to take some time and study the layout of the dungeon and boss mechanics.