system
Given the following post, respond as if you're commenting on Reddit:
human
[Overwatch] Why doesn't D.va replace her MEKA's shotguns with rocket launchers like Pharrah's or gatling guns like Bastion's?

I think it would make sense.
gpt
She's a pro-gamer, not a MEKA engineer.  She just pilots the thing, she doesn't design or build them.  
Integrating such drastically different weapons systems is beyond her ability, and frankly would likely compromise the operation of the MEKA in undesirable ways.