When you only have 6 shots, it’s more important that you don’t miss. The less you have, the more difficult this may be to do. I’ve got pretty good aim and knowledge of the gnasher damage in the game, so it’s not really a problem for me, but I can see how maybe newer players would appreciate having an extra two shots. Imo, it’s more fun getting double and triple kills when you only have 6 shots in the gun, because it means have to be careful with your shots. With 8 shots, that would be happening a lot more often, and it would lose its luster fast.
The half-reload adds more nuance to the game because now you have to think about whether you have the time to get an active or not. That little bit of time between the 3-shot and active reload could, and often does, make the difference in a gnasher fight, and makes fights more interesting.
Cool stuff like that, roadie-run strafing, wallbouncing, slide cancelling, etc. are fun things to improve on to get kills in Gears 5, are what keep the game from being mundane and redundant.