I've been working on a server that I intend to open only in Open.mp, and includes DL resources.

I believe that it should be up to the devs to decide what to do on their server.

In Roleplay for example, new skins are crucial (and we usually use only low poly, q keep the face of the samp.
Objects: many buildings of the GTA itself, but with open interiors being made, graffiti, furniture etc ...

And many are also waiting for the opportunity to add new cars, weapons and animations.

Whether they are from the GTA environment, it is the server's discretion.

If the server you play on, add non-sense stuff, complain or look for another one.
You can't limit the whole community because of some servers that will add nonsense to the samp.