Site Theme - I've already read the mega merged threads

[IronPeacockWork]

1) I already know we're down to 2 pre-chosen themes to choose from. (So woe, much arrrgh)

2) I've already looked at where to change the theme, and found just 2 options. 

3) I see there's an offer for hiring a professional to change the theme/appearance of the site. 

but 

4) If the professional can do it once access is granted, why can't I do it myself? Or are the professionals limited to the same options I already have?