Really the only difference between "residential" and "commercial" plans should be service guarantees. I do not expect Comcast's residential cable service to have any particular guarantee of service; if I had a commercial contract, I would certainly demand some sort of guarantee about available bandwidth and uptime. That is what we have now, more or less.
To put it another way, suppose nobody gets any service guarantee with their residential connection. Why should it be acceptable to say, "How dare you maximize your use of this, when it reduces availability for everyone else?!?" Nobody gets a guarantee of service at all.
Now, if we do get guarantees about our minimum service level, then there is an easy solution, which is to just reduce throughput for "heavy users" to the point where everyone else is getting their minimum guaranteed service. That would not be so bad at all: minimum service guarantees rather than maximum service limits. Of course, once you start making guarantees like that, people start expecting you to follow through and your ability to grossly oversell your network's capacity is constrained (what a tragedy).