Off the top of my head;

* No Active Directory/SAML/other SSO. * Gaudy/gamer orientated look-and-feel, messages and notifications is hard to sell to business. * No/Poor implementations of "Enterprise Features" (read: eDiscovery, DLP, etc.)

Of those the first and second are arguably the most important as it is often a requirement for businesses of any size. The third is a bit more larger/enterprise-y business.