The specific rationale wouldn't be something one could really explain in less than a few pages for each of those.

The overarching reason is that each of these books had a huge effect on intellectual and cultural history across a long span of time. To demonstrate that, one would need quite a bit of space, and ultimately it would amount to giving someone an entire education in the intellectual history of most of the world over the last 2500 years.

It seems rather futile in any event. Pointing out the highlights of Plotinus' influence would involve referring to a large number of other authors and texts and movements that are even less well known, e.g. Marsilio Ficino, the Corpus Hermeticum, and Renaissance Neo-Platonism.

I am pretty sure that for most of the authors, however, a good Wikipedia entry will throw out a few sentences that give someone an idea.