It does seem a pain and ridiculously expensive to pay an attorney for this, but there are some good reasons to do so. As noted previously the requirements for a will to be valid can be a little tight (e.g., witness requirements) and vary state to state. In the disaster scenario where you and your wife are both gone, you'd likely want the will to provide for setting up trusts for the kids (otherwise they'd get everything at 18 and be able to go nutso). Getting the right language inserted, and allowing for backup scenarios for trustee, would have been something I would not have wanted to do on my own.
Also, my "package" included a durable power of attorney, a living will, and a medical power of attorney. These are important documents that you also can get via legal zoom or others, but making sure they are correct is either a lot of work or a gamble.
Finally, my attorney did give me some additional advice that was much appreciated. As an example, she gave me the correct designation for our life insurance policies (in the event my wife and I both go in a blaze of glory) - if you provide for a trust in your will, that might be the desired (backup) beneficiary for a life insurance policy which is outside of a will.
With all that said, you could DIY, but I think it'd be a lot of work to be completely confident you've got it right. A single shingle attorney who specializes in wills would hopefully be an affordable and better solution - they've turned this process into a production line and would be up to speed on everything you need and all of the current requirements / laws.
As a middle solution, you could study available materials (e.g., the library reference) and then get your information and documents completely organized to show an attorney that they won't be going through a ton of iterations or teaching you from scratch (they're largely just dropping your stuff into a template, after all). That could allow you to both understand what and how well they're doing and negotiate the price down a bit.