Opening this up is a sure way to get the servers blacklisted. Such mail are detected as bulk and the server IP could get blacklisted. All these configurations are for the benefit of the customers.
If the server IP gets blacklisted, all outgoing mail will be affected. Thus the number of recipients per mail is restricted, please read here for the exact value. And the total number of mails sent in a day is restricted.
We assure you that we have experienced it for corporate use, our defaults are more than sufficient. A workaround we recommend is that you do not use a regular client to send bulk mail. Instead use a PC based bulk mail software, which will do a mail merge and send the mail via the servers. You can do a search on the Internet for this. Alternatively, you can subscribe to a bulk mail service provider just to send these bulk mail.