rahmanbar,
In answer to your questions, Marriott Corporate Headquarters is in charge of maintaining the website, not the individual hotels. Therefore, sending emails this way is a more direct way to communicate. And as Socrates mentioned previous, not all hotels have a general email address for that property.
Another thing to consider is the aspect of what hotels are responsible for everyday. Each hotel has duties such as pre-blocking rooms, check guests in/out, help people on the phone, etc. It is one thing to answer the phone or read a piece of paper off the fax machine. It is another to gain access to and maintain a general email box.
Also, keep in mind that the people handling your emails sent via the web have been specifically assigned to do so.
I assure you that I do appreciate all the comments and suggestions from everyone! I will be sure to pass them on.
Sincerely,