What taxes really ought to be for, in many people's eyes, is funding government services. To do that, you want to find tax bases that are broadly acceptable to the population, have broad bases and have preferably quite low rates. When we have very substantial increases in government spending driven by increases in operating costs—Tim Sargent alluded to this earlier—and now we're seeing interest expense mounting again, there's a lot of strain on the tax system. Naturally people look ahead with some concern about how high rates are going to go.
If you also have this feature of the tax system that, rather than being used simply to raise revenue in the most acceptable and economically non-distorting way, it seems to be targeted towards whoever might be unpopular at the time, then that creates a very troubling environment for people who are wondering about making a long-term investment, because the environment they're operating in is so clearly not reliable. It's volatile.