Hitting is, far away away, the most important thing in 4e. Not for the damage, but for the riders on nearly every power. Despite the fact that the Dwarf was -1 to hit over every other optimal choice for a Fighter (and debatebly a -2 since you wouldn't ideally use a +3 prof weapon as a Dwarf), they were still optimal for many builds.
This change takes the Dwarf from top tier Sky Blue, to Gold. There is no mechanical reason, ever, to play a Str/Con Warden who is not a Dwarf with this change. Ditto a lot of Fighter builds. Str/Con Runepriest, ditto. Dwarves have the best feat support of any race barring maybe, maybe, Eladrin.