Not all big downloads are illegal. Recently i purchased crysis warhead on steam, thats over 10GB download, you said 2Mbps is more then enough, well it would take ages to download 10GB like that. On my 20Mb connection it didnt take that long at all.
So dont say there are not legit reasons to needing big download speeds. Also, as the statement that VM should fix their current services first, well if you think about it, if heavy downloaders move onto 50Mb connection which is using DOCSIS 3, then that will ease the load on all other connections, possibly allowing VM to reduces the traffic management.
Also as i say in all threads like this, faster connections are not just about downloading MORE stuff, some people want a faster connection to download the normal stuff they download faster. So impatient people will also be able to take advantage of 50Mb.