Some of this was an oversight per a tweet by Mike Mearls. The case cited is the omission of Eldritch Blast from the Warlock cantrip list.
The remaining "missing" content should be addressed at the 15 January Q&A on reddit.
You will also find that Artifacts (p. 256 SRD 5e) are limited to the Orb of Dragonkind. That item, while it lists the random properties as 2 minor beneficial properties, 1 major and 1 minor detrimental property, the SRD does not include the tables for those properties.
Another example is "The Apparatus of the Crab" which looks like a replacement for "The Apparatus of Kwalish" in the DMG. While the A of K is not listed in the Product Identity items on page 1 of the SRD, the intent appears to be to make distinctions between the three core books and the SRD. This intent is confirmed by Mike Mearls' tweet of 13 January: "Intent of SRD is to develop new content, especially archetypes."
