That's not the modern Republican platform. Both major parties want stronger central government in some instances, and weaker in others. They just differ in which instances are which.
And they're like that because most people (voters in particular) are like that. Everyone wants stronger government control and regulation over the things they personally dislike, and less control over the things they do like, and they vote for the party that matches those preferences.
Most Republican voters like and dislike the same things, while Democratic voters tend to have much larger variability (outside a core set of things.) It's why the GOP has an easier time hanging on to power than the Democrats do.
And they're like that because most people (voters in particular) are like that. Everyone wants stronger government control and regulation over the things they personally dislike, and less control over the things they do like, and they vote for the party that matches those preferences.
Most Republican voters like and dislike the same things, while Democratic voters tend to have much larger variability (outside a core set of things.) It's why the GOP has an easier time hanging on to power than the Democrats do.