VPNs these days are one-click to establish and can be setup to use the same credentials as a work machine's login. You can often have them remember your credentials too so that there's no extra work involved, though this should be limited to situations where employees encrypt their file systems a la FileVault or BitLocker.

I agree that it's becoming less necessary as more and more services use strong, end-to-end encryption. However, using a VPN reduces the attack surface area of a network. SSL guarantees that nobody can eavesdrop on the communication but it doesn't guarantee who you're communicating with. Restricting access to the VPN and internal networks means that any 0-day bugs have little impact on your security as less services need to be public-facing.

The biggest threat with telecommuters is that you leave security up to them and who knows what trojans/rootkits lurk undetected on their machine to your antivirus/antimalware software.