Obama was a Senator and the defacto leader of the Democratic Party, so he definitely had a say in a way completely different than Trump in the Fall of 2008. Bush made the right call, but it was mainly policies pushed by Obama and the Democrats.
Yeah, deals are micro-economics. I don't think lower personal income taxes will have any impact on them. Lower taxes for businesses may decrease my deal flow (I do renewable energy finance now, but have done all types of finance in my career) because the deals are supported by federal investment tax credits. There are relatively few businesses outside of the financial sector that can use the credits. And if tax rates go down there will be even less federal tax obligations to use the tax credits against. Again, no one in business that I work with thinks that lowering tax rates for businesses results in more taxes paid to the government. But as you point out we are doing deals which is micro economics. Maybe we don't see the big picture.