Why are we forced to update to 8.1?

I wouldn't call it forced. I haven't seen any proof so far the update to Windows 8.1 has become a mandatory update. I've just seen that the reminders become more frequent as you keep putting off the update. You can always turn off automatic updates in Windows and skip it completely. I would not recommend this as it leaves your computer vulnerable to bugs/exploits but that's your choice.

I think there's ample evidence in these forums that the 8.1 update is being forced.  There are dozens of users who tell the same story, too many for it to be coincidence or user error.

Although I do see from various posts here and around the web, it is being rolled out to everyone at this point. But I am sorry to say, that if there is an inability to support VPN access with the latest operating system then that should be your main concern and not Microsoft's rollout schedule. You should not have to resort to having a vulnerable PC because of some company's inability to support their products.

Unfortunately I have zero influence over when 8.1 support for VPN will be available, but I should be able to influence what version of the operating system I have on my own computer!

By the way, Microsoft has promised to provide security patches for Windows 7 until January 14, 2020, so it is disingenuous to imply that my PC is vulnerable.

In a lot of companies, you have zero influence on what operating system you have. The IT Department usually rolls out what everyone else has which might be Windows XP or Windows 7 (depending on what licensing deal they bought with Microsoft). If you have a small company though, you can usually buy whatever store bought PC you want.

And I am not saying that your PC is vulnerable running Windows 7. I am saying it is vulnerable staying at Windows 8 and not receiving the Windows 8.1 update. You need to be at Windows 8.1 Update (1) to receive future updates.

I HATE Windows 8 period!   Currently I'm running Windows 7 on my PC, personal laptop, and business laptop.  I bought a laptop for my college student grandson, and I hate it.  I'll go to MAC before I go to Windows 8.