Ya i indeed i agree with you, just a text.exe will do its work. However this app was made for the pc which have touchscreen like (surface windows 8). in order to use pen on it and for scratch papers as you mentioned. This is the app purpose i suppose.
in my opinion the only case to buy new sound card, for producing and composing music purposes.
And that can be done by connecting external sound card from pc to speakers. Ex: M-Audio Fast Track pro. which is connected by USB.