Corporate users certainly do. So do consumers who use public wifi regularly and care about their privacy. It would be an option, just like all the others. Would it really be used by fewer people than text size? I would wager that 99% of people set that once then never touch it again. Or scan QR code? That can be done in the camera so just click the camera shortcut.
Edit: I thought maybe the new Shortcuts app would make this process quicker, but it seems like you can't turn VPN on or off through that app either.