Because all of these suggestions require developer resources. Doing a quick web search it is estimated they have ~150 employees. A lot of triple-A studios have thousands or ten of thousands of employees. So they are relatively small game studio.
Also note that they are adding more game modes, mode warbonds, and the game is multi-platform and multiplayer. The dev team is relatively small compared to other game studios.
The game engine the game is built in is discontinued and I believe is unsupported. IIRC they are rewriting the game in UE5 because of the issues with the unsupported engine.
A lot of people have problems with Arrowhead (there been some drama between Arrowhead and the community). The install size of the game while a problem wasn't like the top problem. Bigger issues in my mind as someone that plays the game regular is:
e.g.
- The newest updates to the game with some of new enemy types which are quite unfair to fight against IMO (Dragon Roach and the War Strider).
- The other complaint was performance/stability of the game was causing issues with streamers PCs. Some people claimed the game was breaking their PCs (I think this was BS and their PCs were just broken anyway). However there was a problem with performance in the game, which was resolved with a patch a few weeks ago. That greatly improved the game IMO.