Yes, if you can split your income up over multiple years it will be to your advantage over earning it all in one year.
The reasons are as you mentioned, you get to apply multiple deductions/credits/exemptions to the same income. Rather than just 1 standard deduction, you get to deduct 2 standard deductions, you can double the max saved in an IRA, you benefit more from any non-refundable credits etc.
This is partly due to the fact that when you are filing your taxes in Year 1, you can't include anything from Year 2 since it hasn't happened yet. It doesn't make sense for the Government to take into account actions that may or may not happen when calculating your tax bill. There are factors where other year profit/loss can affect your tax liability, however as far as I know these are limited to businesses. Look into Loss Carry Forwarded/Back if you want to know more.
Regarding the '30% simple rate', I think you are confusing something that is simple to say with something that is simple to implement.
Are we going to go change the rules on people who expected their mortgage deduction to continue? There are few ways I can think of that are more sure to cause home prices to plummet than to eliminate the Mortgage Interest Deduction. What about removing Student Loan Interest? Under a 30% 'simple' rate, what tools would the government use to encourage trade in specific areas? Will state income tax deduction also be removed? This is going to punish those in a state with a high income tax more than those in states without income tax.
Those are all just 'common' deductions that affect a lot of people, you could easily say 'no' to all of them and just piss off a bunch of people, but what about selling stock though? I paid $100 for the stock and I sold it for $120, do I need to pay $36 tax on that because it is a 'simple' 30% tax rate or are we allowing the cost of goods sold deduction (it's called something else I believe when talking about stocks but it's the same idea?) What about if I travel for work to tutor individuals, can I deduct my mileage expenses?
Do I need to pay 30% income tax on my earnings and principal from a Roth IRA? A lot of people have contributed to a Roth with the understanding that withdrawals will be tax free, changing those rules are punishing people for using vehicles intentionally created by the government.
Are we going to go around and dismantle all non-profits that subsist entirely on tax-deductible donations?
Do I need to pay taxes on the employer's cost of my health insurance? What about 401k's and IRA's? Being true to a 'simple' 30% tax will eliminate all 'benefits' from every job as you would need to pay taxes on the value of the benefits. I should mention that this isn't exactly too crazy, there was a relatively recent IRS publication about businesses needing to withhold taxes from their employees for the cost of company supplied food but I don't know if it was ultimately accepted.
At the end of the day, the concept of simplifying the tax law isn't without merit, but realize that the complexities of tax law are there due to the complexities of life. The vast majority of tax laws were written for a reason other than to benefit special interests, and for that reason they cannot easily be ignored.