It's actually pretty fair.
The scenario -
I come home at 5:30 - I go to check my emails, surf a few pages on the web, maybe listen to some online radio, play an online game, make a voip call to a relation in the states, make a few bids on ebay, download the odd mp3 and turn my computer off for the night.
Now this represents 95% of people on the VM network, what if their emails took 5 minutes to download with time out errors, what if pages took 3 or 4 attempts to load, internet radion was constantly buffering, my online game was full of lag and i was constantly getting disconnected, my voip call was choppy and bad quality, my ebay bids timed out and i lost my bargain.
Now they pay for a connection which they expect to be usable and 24/7, how is it fair on them...remember this represents the majority. What if 20% of their 95% of users left because of bad quality service?
What should vm do? increase bandwidth? Ok so they do that and everyone is happy except that vm have to increase their prices to cover the costs, they lose a lot of their 95% of customers. If they cap it in the way they have done they might lose a few users but it will only be a small portion of the 5% so it's the best option for vm. Remember they are a business and they need to make money to exists, unless you want some kind of national broadband service lol