Wizards definitely designed the races to focus on certain classes. I consider it a design flaw of sorts. The positive being that this sort of design ensures a large variety in races being played in 4E as a whole. The negative being that I could never see myself taking Gnome, or Eladrin, Half-elf, Halfling etc for the above fighter build due to the current design.
Though I've never implemented it, I like the house rule of using one of the two Ability boost options per race as a mandatory, and allowing anything else as its secondary. Thus opening up a lot more options to the players to choose from without sacrificing their vision of 'optimization'.
See, I don't really agree with that at all. We could further increase the versatility of class+race combos by just eliminating stat boosts entirely (or giving +2 to any two stats you want), but then what's the point of even picking a race?
Yes, a Dwarf wouldn't make a good Mage, and a Gnome wouldn't make a good Fighter (have to disagree with you on Eladrin and Halfling though...there's a LOT of options there, you just need to do careful planning for feats and Paragon Paths), but isn't that part of the point?
What makes a "Dwarf" a "Dwarf" anyway? Is it just their height, or is it that they're known as a wise and stalwart people fond of living a hard life underground? If it's the former, then Halfings and Gnomes are the same, and therefore we can combine them into one race (yes, I realize Dwarves are technically M size, but they are kinda short). If it's the latter, then how does a Dwarven Wizard fit into that? They're not a natural fit for Dwarves, and they shouldn't be! They're a much better for races like the Deva (who could've spent lifetimes studying magical tomes) or Eladrin (who come from
another plane).
Now, you can still make a Dwarven Wizard, you just need to be creative. For one, I would probably just try to live with the fact that you've got a 16 starting Int, and not waste the points on the 18. If, on the other hand, you decide to go for broke, you're not totally out of the running. CON and WIS are both useful secondary stats for Wizards, namely Summoning (Staffs too) and Orb Wizards respectively. He won't be as good as the Eladrin Wizard, but he could multiclass into something like Invoker or Cleric for some extra power.
Point is, some race+class combos work better than others, and that's partially a design choice. Dargonborn have an ancient connection to Dragons, which makes them natural Dragon Soul Sorcerers (mechnically shown with a +2 to STR and +2 to CHA). They're also a very large and imposing race with a long martial tradition (mechanically shown with a +2 to STR, which is great for Fighters, Rangers and Warlords) and their fierce personality makes them natural leaders (mechanically show with a +2 to CHA, which is good for some Warlord builds). This by no means indicates that you MUST be a Dragonborn to be a Sorcerer or a Fighter. It just means that some race+class combos have a natural synergy, whereas others don't. Just as some people have a natural affinity for English or Math, but not necessarily both.