1) If the income after retirement is lower than now, conversion from traditional IRA to Roth IRA is not recommended;
2) If you are young and just start your career, you income may not be higher than retirees;
3) A lot of people are not qualified to contribute to deductible IRA, but the threshold for Roth IRA contribution is much higher, and it is practically eliminated from 2010;
4) The gain in Roth IRA account will not be taxed while the gain as well as the contribution in deductible traditional IRA will be taxed as ordinary income.