Why use ++i instead of i++ in cases where the value is not used anywhere else in the statement?

I'm well aware that in C++

int someValue = i++;
array[i++] = otherValue;

has different effect compared to

int someValue = ++i;
array[++i] = otherValue;

but every once in a while I see statements with prefix increment in for-loops or just by their own:

for( int i = 0; i < count; ++i ) {
     //do stuff
}

or

for( int i = 0; i < count; ) {
    //do some stuff;
    if( condition ) {
        ++i;
    } else {
        i += 4;
    }
}

In the latter two cases the ++i looks like an attempt to produce smarty-looking code. Am I overseeing something? Is there a reason to use ++i instead of i++ in the latter two cases?