For top fraggers eliminating that RNG means they can always directly engage and more than likely come out on top, and rely much less on outmanuevering and outsmarting their opponent. It means they can rely less on their teammates to watch their backs and apply additional pressure. It means they don't have outplay and outgun their opponent if they can simply outgunplay them.
Make no mistake: being the better shot is and should be an option in this game. It's the raw, bloody final option or even the option number two for the crackest of the crackshots. But this makes it an option too available and available to too many. And easily available and openly exploitable to fucking cheaters L-M-F-F-D-A-O. Laughing my fucking fucking dumbass off.
To answer your question specifically I think they're doing it because it's the easiest solution to the alignment issues and it appeases some vocal pros at the same time. Two birds with one stone; a "win-win" for the apparently perpetually undersourced and at this point I say partially incompetent Siege team.
I think you are over analzying the impact of predictable recoil vs. strategy way, way too much.
I have no idea how this is going to reduce strategy, in any noticeable way, at higher ranks and pro play. If Siege was a high TTK game, maybe strategy would be impacted. But as it stands, given the sheer speed at which you can die, I really do fail to see how and what tactics will be pushed down in favor of simply outgunning the opponent.
Maybe tactics will shift, given the larger consistency in recoil, but I don't see how they would get reduced in favor of outgunning the opponent. Peeks might change, the way attackers approach a building or objective might change but that seems completely fine to me.
Like, an alternative way to put it is basically: for top fraggers, before, sometimes they'd get a kill with a strategy and sometimes they wouldn't due to the recoil. Now, given the more consistent pattern, they are more than likely to get a kill using that strategy.
The strategy hasn't changed. And maybe this will force, for example, the defender to play differently rather than leaving his fate up to that RNG.