I'm aiming to complete the challenge and get all 10 souvenirs, only because it is my first GC.com souvenir challenge, but also because I want to get out geocaching and this is a reason to do so.
As for yourself, only do it if you want to do it, not because someone has told you that you should be doing it. If you collect some souvenirs because of your regular caching schedule, well done! If you go out specifically to complete the challenge, well done!
How you do it is up to you, and only you!!!