I literally believe we would likely get the opposite of every possible negative thing you mentioned; mostly because I think the cause of most software problems (or more specifically, the difficulty of discovering and fixing them) comes directly from the monopoly and monopoly-like players that currently exist.

I'm aware that a world in which e.g. Microsoft was actually sued to the extent of the damage it has caused is hard to envision, but I can't help but think breaking that sort of thing up by whatever means gets you more visibility, more localism, more shallow bugs, etc.