It may seem like the correct solution, but it's just as easy to make an email account as it is to make a VW account. It may take a few extra minutes, but once it's done and they've verified their new accounts, the cheats don't have to remember the email password at all because they've already achieved their purpose.
Totally agree it's easy to create an e-mail account. My point is, it may take them a good 5 min's to setup the e-mail account, create a VW-3 account and verify by that new e-mail account. Yes its easy to do but time consuming for repeat offender's whom may currently, create an account get banned re-enter with new account to solely cause trouble get banned and repeat in less than 30 seconds.
My proposal would at the very least give them some work to do which would not be as enticing.
At present 30 second set up, 1.5 mins kick: Average Ratio 1/3
My proposal 5 mins set up, 1.5 mins kick: Average Ratio 3.3/1
Hardly worth a trolls time to continue as the swing is now against him/her with regards the effort and time to cause trouble for such a short limited period.