I still don't like the idea. I just don't buy into the idea of a warlock being a tank. It's just my opinion though. Putting them in demon form will also cause the same problems they're trying to fix with druids. You don't get to see your shiny new equipment. I did see boom chickens are going to get astral form now. If they can make a different form that can show equipment, it might work.
Seeing equipment is not that big of a problem, actually, you should have seen the shitstorm that happened when they removed tree form as a constant shapeshift. It got so bad they are adding it back in as a Glyph for MoP. Druids like their shapeshift forms, it's one of the reasons they picked the class. Warlocks I talk with are fine not seeing the gear in demon form, the only wish I see is they want a valid female version of the model for female characters.
You don't have to like the idea, but at least be straight about it and admit, from a standpoint, it makes sense for a big hulking demon man to take a lot of hits.
Now to answer what you feel will improve the game.
- Force people to be at an instance entrance to queue for it. It would get people out of the capitals and into the world. It could also make for some interesting pvp situations in pvp servers. Maybe once you're 5 or 10 levels above the instance you can queue from anywhere.
They attempted something like this by making it that discovering the dungeon was a requirement to even queue for it. Players hated it so much that the requirement was removed in the very next patch. The LFD and LFR tools have been majorly praised as one of the best things to happen to the game in years. You are not going to see people want to revert to the old methods of traveling to dungeons, and any that do are so rare it wouldn't be feasible to cater to them.
- No flying in the capitals. God damn that's annoying.
Why exactly? What is so bad about people using flying mounts in capitols? Be aware, I can personally live with this as I am used to it from the old way Dalaran used to work, but I never found it to be such a big deal that having people flying around "annoys" me. It's all just quality of life improvements.
- Slow down flying, or make flying mobs that attack you more common. Or both.
Not going to happen. There are many that think the mount flying is already becoming way to slow compared to the world size. As for flying mobs, most people enjoy flying because it is a method of travel that does not have you attacked every few feet. You will find some that consider it boring and want to have "danger" while traveling, but they are few and far between then those that use flying as a safe method of general travel. Again, this would detract from the game in the long run rather then add to it.
- More world bosses. Maybe some that roam an entire area like the fel reavers. I nearly shit myself the first time one of those snuck up on me. I haven't played much in cata, did they add any of these?
This is a wish you will be getting, as adding world bosses like Garr in Cataclysm were seen as a positive thing. They will be adding more in the new expansion and are going to push for the Horde and Alliance to compete over killing them.
This wish, technically, was already granted. Dalaran used to have city portals to all major cities, but they removed them in favor of only a portal to Stormwind, since that was the new hub and the didn't want people just porting to Dalaran or Shattrath. However, they are not going to remove all the portals they have, as one is a perk (Mage Portals) and the others are required to be able to even do Cataclysm content (Cataclysm Zone Portals). To be honest, I want more portals, I just want the portals to be more spread out. Example, those Emerald Dream trees in Ashenvale, Feralas, Hinterlands, and Duskwood I felt should portal between eachother for higher level druids.
In the end, they will not cut down on portals to an extreme. You will still have basic required portals for zones or class perks, and likely in MoP we will have portals to return to the main continents from Pandaria.