I noticed that the API allows you set to the username field to values with special characters. In example, you can set username to a'b@example.com. However, the CMS Desk does not like this value. The CMS Desk generates the following error:

Please enter a valid user name. The user name can contain only alphanumeric characters and some special characters (_, -, ., @, \).

If I modify the CMS Desk Users module (CMS Desk > Administration > Users > Edit user > General) to allow special characters, are there any drawbacks to doing so?