I think the culture has simply shifted (in the tech world, that happens quickly). Apple bundles Safari with its OS, yet no one cries foul. Yet when Microsoft did this 10 year ago it was investigated for antitrust.
The question is, can you use your ownership of the platform to destroy competitors of apps on that platform? When does it cross into "monopoly"? I have no idea. It seems fair to me that the creator of a platform should be able to introduce new applications and place them in a preferred spot for all to see (e.g. facebook's own apps). As long as this was clear to everyone from the beginning. However, strong-arming OEMs and others into specifically doing anti-competitive things on your behalf is probably wrong.