First - for anyone else reading - An IRA that has no beneficiary listed on the account itself passes through the will, and this eliminates the opportunity to take withdrawals over the beneficiaries' lifetimes. There's a five year distribution requirement. Also, with a proper beneficiary set up on the IRA account the will does not apply to the IRA. An IRA with me as sole beneficiary regardless of the will saying "all my assets I leave to the ASPCA." This is also a warning to keep that beneficiary current. It's possible that one's ex-spouse is still on IRA or 401(k) accounts as beneficiary and new spouse is in for a surprise when hubby/wife passes. Sorry for the tangent, but this is all important to know.
The funneling of a beneficiary IRA through a trust is not for amateurs. If set up incorrectly, the trust will not allow the stretch/lifetime withdrawals, but will result in a broken IRA. Trusts are not cheap, nor would I have any faith in any attorney setting it up. I would only use an attorney who specializes in Trusts and Estate planning. As littleadv suggested, they don't have to be minors. It turns out that the expense to set up the trust ($1K-2K depending on location) can help keep your adult child from blowing through a huge IRA quickly. I'd suggest that the trust distribute the RMDs in early years, and a higher amount, say 10% in years to follow, unless you want it to go just RMD for its entire life. Or greater flexibility releasing larger amounts based on life events. The tough part of that is you need a trustee who is willing to handle this and will do it at a low cost.
If you go with Child's name only, I don't know many 18/21 year old kids who would either understand the RMD rules on IRAs or be willing to use the money over decades instead of blowing it.
Edit - A WSJ article Inherited IRAs: a Sweet Deal and my own On my Death, Please, Take a Breath, an article that suggests for even an adult, education on how RMDs work is a great idea.