I see the edit you put above about not having to do with Roths (or maybe I missed it the first time I read your post)
Still... a 401K is going to give you a way better result in the long run than paying taxes the whole time.
Here is an example to demonstrate:
Lets make some assumptions (please feel free to give your real numbers if they are far off from these). Lets assume your top tax rate is 25% and lets assume you want to set aside $5,000 every year. Lets also assume that the market will return an average of 10% a year for the next 40 years.
If you invested that $5,000 every year into a 401K you'd end up with $2,233,535 (today's dollars mind you) but if you invested it the exact same way in a taxable account you'd end up with $1,142,577 in today's dollars (because you're paying 25% tax on the compounding growth)
So the fact that you gave up the tax free growth cut the retirement funds in half.
Lets assume from that point on that you were going to draw 4% a year from your 2 million 401K account... that comes out to about $100,000 a year. Taxes would need to be well north of 50% on average for the $0-$100,000 income level to make that look less appealing than the smaller taxable account.
What is more... is that the 401K account continues to grow tax free, meaning if you're still getting a 10% return you are paying no taxes on the growth of the large account... while the $1.1 million taxable account that you're trying to use in its place is being taxed every year at the presumed higher rates in the future (greater than 50%?). So the higher taxes in the future are screwing you whether the money is in 401K or not.
Hope that helps.
IMO, the only possible way a taxable account would be better is if the funds you are stuck with in your 401K are horrible and have very high expenses (typically not the case), and you think your growth will be greatly reduced by investing your money there.
Paying no taxes on growth is a freebee from the government that no one should give up voluntarily.