That is a good question. It's been 5 years so I'm a bit fuzzy on the specifics, but some it has to do with official releases and others with me being a perfectionist and I wasn't 100% happy with it.
One of the reasons I started that mod was because cannons didn't have damage or shooting speed research yet. I added it into my mod and literally a few months later they added a official option. I also had a advanced personal roboport (among other things) and they added that too.
As far as not 100% happy with it, adding a rocket and cannon turret was tough because I'm not a artist and didn't know how to do much for custom animation or sounds. Amazingly I made a particle drawing and a new sound file for the cannon turret. It looked and sounded decent actually.
Over the years I frequently looked back on the files (github repo) and thought of refreshing it but then I'd look on the mod portal and most of what I did is covered by someone else and usually with much better visual style. I'm also not a programmer, more of a tweaker, though you can do A LOT with tweaks. Bob's mod has very little actual programming for instance.
Anyway, I released this mod because no one else is doing this. Stock artillery turret is trash. Irritating logistics with the 1x stack size and it has no differentiation vs the arty wagon. I envision a emplaced gun as having longer range (I'd say more accurate as well but that is moot in this case). I'm open to other tweaks though I'm limited in what else I can do for artillery without modifying the ammo (or adding a new ammo).
