I've always bucked the basic 401k menu trend of "fewer investment options is better for participants".
That basic understanding of participant behavior was based on the false logic of assuming that participants are investment savvy with fewer investment options and somehow lost that investment skill as more options were added. The truth is, most participants do not have the required specialized knowledge, interest and time to properly understand a single investment option, much less any varied number of them. Thus, evaluating participant investment understanding and results based solely on the number of funds in a plan (which is extremely common thought in this industry) is simply bad group think.
This article "Expanded 401(k) Menu May Nudge Participants Towards Better Outcomes" is one of the first I've seen (against a backdrop of hundreds of the "fewer is more understandable so better" articles) to address this.