octopi is installed because of 2 reasons:
it (especially octopi-notifier) is needed to update the list of manjaro mirrors. without that list, you would not be able to download the latest packaes (or download them extremely slowly). this part of not working perfectly yet, but there have not been any efforts upstream to fix that. we will see what will happen.
if you use this ISO as a rescue system, you sometimes need extra software to do that. octopi (and preinstalled AUR support) is great for that.
we do not want the ISO size to be bloated just to show off all available software. the ISO size could easily increase to 1.2-2.0gb if we did that. in my opinion, this is unacceptable.
this net edition is aimed at experienced manjaro/arch users, which means that most of them already know about manjaro settings manager.
but you are right that octopi (and not octopi-notifier-qt5) could probably be removed. we could also remove AUR support and some parts of lxqt (including the theming).
but to be honest, i like the current live system: it looks nice and has some comfortable features already preinstalled. if we removed all bloat, it would shave off about 50mb of the ISO size, but we had a shitty looking live system, without AUR support.