I propose at the very minimum make an effort to let people add Analytics in a normal way as is done with 99% of premium WP themes. Laypeople don’t exactly know what “hooks” are.
There are significant advantages of using hooks over having a dedicated field for just Analytics. We have to consider ‘what ifs’ – such as what if Google changes the way you add their codes in the future? It would be awful to have redundant code for a dedicated area in the Theme if that ever happened.
If your only using Google Analytics then google only provides you with a single script – in that case you only apply the steps require for the ‘first block’ of code.