Hi Liorlankri,
I use web services because it helps me create modules of code.
If any changes need to be done to the code in webservice,the InfoPath form need not be republished again.
It really helps me since I use regform to make my form full trust and deploying such a form in sharePoint needs a work around.
So publishing each and every time I make a change to the code is a tedious job.
So in case of webservices to access databases or SAP Bapis,I can easily modify my queries in the webservice.No touching InfoPath code is required.
regards,
Abhishek