> The issue is that, for any company without thousands of employees (heck, probably even some of these are guilty), the VPN is often the only barrier to the entire network.

Sorry, but what? I've worked in multiple small companies where the we where less than 5 system administrators and inside the vpn we had encrypted traffic and ldap auth on everything. It's a few days job for a single person to set everything up this way with open source tools that are extremely well known and documented.