Several things both me about these proposals that occasionally get floated around:
1. They make the implicit assumption that everyone has a sales or use tax, and that people are avoiding it. That may be true in many cases, but not mine, since my state has neither. I don't
2. Similarly, it's unfair for businesses operating here. For a business located purely in my state, it's not a fair burden for them to have to calculate and collect use tax for any of the hundred (cities, counties, states, and various other revenue districts) that someone might be in when they click their mouse to order. I don't mind the "nexus" argument for sales tax (hey, the company chose to set up shop in a state? Then you can learn the tax rules and when to collect them), but extending it to use tax isn't fair. If a state really feels they need a use tax, it should be their responsibility to figure out how to collect it, and not involve companies that don't even have nexus in their state.
3. They talk about simplifying it, but there's already enough cases that I can this not working correctly (person in state A buys a gift from vendor in state B for shipment (from state C) to the recipient in State D).
I say get rid of the sales tax. They aren't necessary, we've got several states (including my own) that get along just fine without them.