In the GUI you will only see packages with a name that starts with "enigma2-plugin".
As a typical user, there is no need so see the others, they are system packages, and should be defined as dependency of a plugin, if and where needed. If you are a non-typical user, you are expected to have enough knowledge about the system and know your way on the commandline.
What we want to avoid is typical users fooling around will all sorts of ipk files, and use either ours on other images, or the other way around. Contrary to popular belief, not all enigma images are the same, so chances are things will fail, and when they do, these typical users come here to complain about it, and wasting our time doing so.
Currently in use: VU+ Duo 4K (2xFBC S2), VU+ Solo 4K (1xFBC S2), uClan Usytm 4K Ultimate (S2+T2), Octagon SF8008 (S2+T2), Zgemma H9.2H (S2+T2)
Due to my bad health, I will not be very active at times and may be slow to respond. I will not read the forum or PM on a regular basis.
Many answers to your question can be found in our new and improved wiki.