I realize you think you are, but you are not.
Just like there are winners and users with the current system. Just different winners and losers.Going to capital gains at ordinary rates but indexed for inflation will have a very minimal effect on the average tax bill, but there will be winners and losers.
I do agree there would be different winners and losers but I don't think it would matter in the big picture.
There is no problem. First, interest income is earned during the tax year just like wage income, and wage income is not indexed. Second, nominal interest rates include expected inflation, so indexing is not necessary on the income. So, there would be a hidden problem with the difference between actual inflation and expected inflation, but that problem is dwarfed by the inherent issue of not indexing capital gains (something you have no problem with).There's a hidden "problem" with the indexing approach, though--to be fair it should be applied to interest, also. That would take a big bite out of the taxes collected on interest income.
Regular rates with indexing would be somewhat fairer but I don't think it's worth the headaches that would come from changing the system. I do not hold a strong opinion either way.
While the interest is earned during the year the money is tied up making that interest--it is degraded by inflation the same as a capital investment is. Thus if stocks are to be indexed then interest likewise should be. What you are missing is that currently you are taxed at your marginal rate for both the nominal rate + the inflation rate. If you index it you're going to do something like halving the tax take on interest.