Okay.
It is not clear to me whether or not you are a DM. In any case, you do not speak for all of us. Preparing monsters and NPCs is the primary form of preparation I do. I would struggle to run a game without a small library of stats that I made myself. And I don't find it excessively time-consuming, because I know the rules and I work fast. If I wanted, I could limit the sources that I used (instead of referencing dozens of books) and do it even faster. If I needed to, I could buy premade stats from various sources (though I personally wouldn't),
Moreover, PF has done something rather nice in creating simplified templates that are easy to apply quickly, which addresses exactly this issue. It shouldn't be a time-consuming process.
He might not speak for every DM but there are many like him and I am one
I think it's good that both sides of the fence can say how they feel and hopefully, WotC can come up with a way to satisfy most of us. Or maybe not. But that's why everybody should speak his mind.
And since you mentioned Pathfinder: You might find some things "quick" and "simplified" but they aren't enough for me. That's just how I see it. People who play Pathfinder tend to see things as simple when others find them extremely complicated.
Personally, it's definitely a game I hope DnD Next does not take inspiration from.
A monster isn't a task. It is a character in the story. A more interesting monster makes for a more interesting story (up to the point where the monster detracts from the story because the DM is showboating). An 'average' monster is not worth the game time for me that I would spend running it. If I'm going to spend time out of my busy life to fight a D&D battle, it had better be more interesting than mowing down some orcs straight out of the monster manual.
That might be where the disconnect comes from. To me, it's not the stat blocks that make the creatures, monsters, NPCs populating the world interesting. There's different ways to flavor things other than stats and rules.
Moreover, as I alluded to above, what else is there to work on? There is campaign prep, getting the setting ready and such, but I don't know what else there is to spend time on outside the game once that's done, and that's mostly done before the 1st session. D&D is primarily an improvisational game. Looking at published adventures, I can't imagine why a DM would waste time creating that much information in advance. D&D rules are mostly about representing living creatures through character stats; it follows that most prep should take the form of character stats of some sort.
That's definitely not how I want to spend most of my prep time. To me it's more about backstory, motivation, context, personality and all the ramifications that come with this. Not to mention how those things are impacted when the PCs are interacting with the world and those characters and creatures.
I do think there is a balance to be had. I'm not saying monsters should be bland. But I'd rather have a stripped down approach that I can build upon and focus on what's important for me.
I'm sure others might prefer something else but heh, this is a good time to tell WotC what we each prefer and hopefully, they figure out what's best.