Why would Devs mods won't just be included in-game?

There's a lot of mods made by devs, and I was wondering, "why not implementing them in-game?"

Some are outdated, like AgentMooshroom5's Snow Plow, but a lot aren't, like Sandy Mountain and Endless Highway by Nadeox1. Or even the Japanese Plates Pack by AgentMooshroom5!

https://www.beamng.com/resources/endless-highway.1427/

https://www.beamng.com/resources/sandy-mountain.2644/

https://www.beamng.com/resources/agents-japanese-plates-pack.30101/

(First two pics by @Nadeox1 and the last one by @AgentMooshroom5)

 

It would probably make the already very large installation package even bigger. I think it would be better if you were free to decide whether you wanted these and many other great mods or not. And if the devs wanted to highlight some of them in particular, they could do so in the featured area.

 

How many times do they need to say that they're not adding mods?

 

One time less I guess. /j
Honestly, I have (like many other) have 0 knowledge in coding/modding. So I didn't knew things like adding pre-existing developer mods would be actually increase filesize and stuff!

 

maybe the mods are just for fun