My opinion on this is simple...
you can't add more skills without introducing new ways to counter or compliment them and IMO it is much easier to create new professions to do this...
more skills and more professions means more diversity, more playability, and more customizability...
and again IMO it is easier to balance newly created skills for core professions by intoducing other professions that have skills to compliment or counter them...
i don't think this game would have gotten as far as it has without the introduction of new skills and new professions... simply haveing new areas and new creatures isn't nearly enough to captivate the majority of us...
each new chapter what i look forward to the most is NOT the new scenery but it is all the new skills for my already existant characters and new professions to try out and master...
though i must admit, personally im hoping chapter 4 introduces more than just new profs, skill, enemies, and land... im hopeing for a more advanced combat system and some overhalls on existing game mechanics... chapter 3 i believe went in the correct direction... but for some reason GW's entertainment value has dimished for my liking... please amaze us...
s

Sound nerdy? You probobly have a good deal memorized already