It appears that the decision of Google is based on the need to limit the number of file types that criminals repeatedly use to spread malware.
Google has already banned many file formats from its Gmail service. Some of the common file formats that the company has banned so far include VBS and VBE. VBS (VBScript) and VBE (VBScript Encoded) are common forms of scripting files that hackers and cyber criminals use to send various types of malware to people.
Other common unusual file formats that Google has already banned from its Gmail service include WSH and WSF. These two file formats, the Windows Script Host Settings File and the Windows Script File, have the capacity to execute once they land on a device automatically. It is this unique feature of these types of files that has made them attractive to cyber criminals who spread malware over the internet.