Except for the eggs (which I would argue are not necessary at all but are due to a false demand created by marketing) it isn't really a convenience. Most people don't need or normally want three egg whites at random times between meals, but they have been trained to "need" it via thought manipulation (a.k.a. marketing).
If people want to know what their diets really need, it usually isn't something like protein or supplements -- it's to stop eating things that contain refined, added sugars and to start eating more fresh vegetables. :)
I don't think that buying a few bags of nuts and dates is more difficult than buying a "nutrition" bar -- it's just a different kind of habit, and one that a person has to actively self-train (rather than be trained in by external manipulations).
It isn't worth debating it too much -- I just find it interesting. I lean towards DIY with food in general.