I've been playing DnD for almost 15 years now, AD&D, 3.0, 3.5, and now 4.0. Always DM'ing.

From a DM's standpoint, 4.0 is the most streamlined the game has ever been. The ease of NPC or monster creation is so radically simplified that you can create MULTIPLE encounters in ONE minute. It has a built in balance feature for every player, as in, someone's not going to be under or over powered at pretty much any point in the game. And, for anyone that plays a non-magically based class, your favorite hero just got three or four hundred new abilities to choose from (sure, you can describe your auto-attack in a different way if you want to, but this gives you new tactical options for combat).

4.0 is honestly like playing a video game. Everything is quick, calculated for you, there's no difficult stacking or priority rules, and with some imagination it looks pretty cool.

That being said, if 4.0 wasn't as quick and efficient as it was, I'd still be playing 3.5.

4.0 lacks the flexibility, customizability, and sheer breadth of options that spellcasters once enjoyed. Plus the Book of Nine Swords added a precedent for interesting non-caster classes (even though it was really just an interest check for 4.0).

As for the various blasphemies, just because something's in the PHB doesn't mean it's common. Tieflings are still pretty looked down on and most still have to disguise their identity if they don't want trouble. In the Deva description, it explicitly states that it's highly possible for a Deva to go their entire life without ever seeing another one.

Don't feel races are getting proper representation or treatment? Talk to your DM, it's their world. Wizards didn't drop in population demographics other than to say that Humans have an overwhelming majority and that races X, Y, and Z are limited to a few hundreds/dozens/individuals in existence.