Indeed, you pay to play a game, but consider, a game is a work of art like a movie. A movie full of action, beginning to end, without a break, just ends up feeling too busy and each action feels less important. There has to be downtime to appreciate the good bits even more; it's called pacing.

You can argue that some of the forced pauses such as group forming was good for the game. (I certainly wouldn't; spending 5 hours to do Sunken Temple with 3 hours of that being group forming wasn't fun.) You can also arguing that removing the need to fly to the dungeons was necessary. But taking out 100% of these pauses leads to the game feeling very mundane. When "chain running" heroics becomes normal, each heroic doesn't feel, well, "heroic". As an example, when one 5-man dungeon took an entire evening (Sunken Temple, Blackrock Depths), they felt special, even if they were Hell and a half to even get a group for. Dungeons you crank out in 15 minutes feel boring and mundane. It's hard to marry "able to be consumed on a limited budget (of time, skill, etc.)" and "epic".

The point where "streamlining" starts damaging the feel of the game is different for other people, but I think many people can agree that not having to explore the world and only needing to stay within the capital cities to do all of your business didn't do much to make the world (of warcraft) feel alive. Streamlining is good, but Blizzard has to be conscious of just how much "streamlining" they are doing, and what it does to the game, and players need to understand the same.