[kayoone]

Why? Even now, you can just forward the guest port to the host and expose it to give people access.

Vagrant share makes the process of doing this super easy which is great, because you don't need to do any of that manual trickery.

[IgorPartola]

Several reasons. First, you are likely behind a NAT. Sure, you can share your Vagrant box with people in your office, but you can't share them if you are working remotely. This has actually bitten me on my team (I work remotely) where I needed to debug a Puppet issue on a coworker's VM and had to try to ssh to his box. What a pain.

Second, port forwarding is fun and all, but why bother when you can do things properly and directly. Your host machine can still control everything and you won't need to do anything manual. All the manipulations that are required can still be hidden behind the simple `vagrant share` command. You can even combine this with a dynamic DNS entry so that you could share not just an IP address but a simple name.

Third, it would be less effort do support this, than to maintain yet another NAT traversal service.\

Fourth, this would speed up adoption of IPv6, something we will all benefit from in the long run.