During usability testing, I often observed people attempting to click the node label (which does nothing) instead of the node icon. At the time, the onclick event was not captured on the node label. I asked about it on the vis.js GitHub issues list, and apparently it was eventually added as a feature. See conversation here:
visjs/vis#824 (comment)
It would be great if at some point the behavior of the node icon click could also work for the node label, assuming that this functionality is now available.