Thank you for your question, I think.
On simplifying the tax system, the general mantra of an economist, probably even an accountant and a tax lawyer, would be that a simpler tax system is a tax system that has a broader base and doesn't have a lot of exemptions. For example, the GST is a relatively simple base with some exceptions, whereas income tax is more complicated.
A lot of the complications in the income tax system and also in the corporate tax system come about because of the way we treat capital income, I believe. If we can simplify the way that capital income is treated in the tax system, it would probably go a long way toward putting tax planning professionals out of business, I would say.
I think looking at things like the capital gains exemption is one place to start. I think also.... I didn't want to get into this too much because it's a relatively technical subject, but the corporation income tax could also be simplified considerably by adopting a much simpler system that leads to fewer opportunities for profit shifting, changing the way you earn your profits, and so on.
These are difficult questions, but in the end I think simplification of the tax system would increase the trust members of the public have in it.