100% agree on this whole article. Especially where it discusses the accessibility to new GM's. I remember trying to customize things in 3.5, and I was very put off of DM'ing. I have no such troubles in 4e. I modify almost every enemy I use, and I have been changing rules and some of the pre-published modules for every session. The best thing I can say is that from an accessibility standpoint the rules in the DM Guide just work.
This is a great write up.