Many folks around here contribute the maximum to all possible retirement accounts before they contribute to a taxable account or to a 529 plan or to an emergency fund (a Roth IRA can be used as an emergency fund) or a car fund or to a house downpayment fund. Here is a poll: viewtopic.php?t=42313
Whether you should too depends on your cash flow. However, there is no way one should start a college fund for children or nieces or nephews until one is making the maximum possible contributions to one's retirement accounts. If you do, you will find that when college comes around for your children that you will be able to pay for it just from cash flow: stop the contributions in those years and divert to the college of your offspring. You will not even have to use savings to pay for college, so there is no need to save for college.
Of course, if you have a high enough income, there is no reason not to put the maximum possible in retirement accounts, contribute to one or more taxable accounts, and even contribute to 529 plans. All those contributions will mean you are living below your means and then you will have choices later in life: Buy new cars, new TVs, retire early, nice vacations, or whatever money can buy. Or give it all away to charity.
It's all about short-term opportunistic rebalancing due to a short-term change in one's asset allocation, uh, I mean opportunistic rebalancing, uh I mean rebalancing, uh I mean market timing.