I can totally understand the inclusion of Tiefling over Aasimar. Demons and devils are wide, diverse and have a lot of interesting traits and powers. A person with demonic or devilish blood is immediately apparent.
But angels? Oh, so hopelessly dull. Just removed for inappropriate reference vision of perfect humanity with wings in most depictions. And a halo. And maybe a harp.... and if one is angel-blooded, then they just lose the wings and thus look like removed for inappropriate reference And what are they going to gain from it? A healing spell or some such?....
Seriously-- if they were going to do people with celestial blood, I would want it to be some interesting looking celestial beings! Give them blue skin, black hair that prematurely silvers and whitens (or, better yet, give them feathers for hair!), they can have the big dove wings but also give them a third eye. And when people have their blood, it ought to be just as instantly recognizable as Tieflings are.
But then.... would it still be an Aasimar?
And Dragonborn are in need of a major redesign. The look of Dragonborn screamed that they were designed based on the stats they were willing to give them. Previous D&D editions have had Dragon-humanoids. Dragonlance had Draconians, Faerun had Dragonkin... the Dragonborn ought to have simply united such concepts under a single racial model.
If they are Dragons, less inarguably so than Kobolds, then give them wings! Give them a bit thick tail. It is perfectly find to say that their wings aren't quite powerful enough to carry them and the tails hinder them as much as help them. And they should come in all the varieties of dragon colors. It would then be up to individual campaign settings to make more of the colors or not.
But, really... if one is saying "dragon people" then the image that pops into one's head isn't muddy brown tailless lizard-people with boobs who can belch an almost harmless cloud of flame or ice or whatever once a day. Such a design could only have come about by thinking about how their 4E stats would function first and foremost.
Also, what's with them being super friendly and cuddly with everyone? Being super aligned to being good and faithful and noble and serving humans like puppy dogs? They are the descendants and armies of the biggest, baddest, most powerful creatures in all the land-- and not worthless slaves like the Kobolds. By all rights they should be declaring themselves the masters of the world, forming up armies to expand the area of influence of their masters-- collecting as much treasure as they can and putting down threats before they come anywhere near the dragons. They should be every bit as off-putting and aggressive as any Hobgoblin or Githyanki. Which shouldn't disclude the possibility that one in a hundred might end up becoming a mercenary perfectly happy to work with other races.
But, still-- their alignment and intentions and position in the world was silly. How is a 8' tall, reptillian warrior not going to be arrogant, self-centered, dismissive of "lesser" races and working to build up empires for their own kind? The very word "draconian" both means "dragon-like" and "cold, brutal and oppressive". They would be a hundred fold better with those obvious tweaks.