There's a difference between what is legal and what is right and the two don't always overlap.
In the case of Uber, their initial ignoring of the laws protecting Taxis I think was a good thing. Though this doesn't hold true for the things they were later accused of.
Yeah, but they also didn't want others to be able to do what they did.
If they really thought they were right, they would be lobbying to remove those medallion requirements for everyone, themselves and the taxi companies. They didn't.
You can only fight a war on so many fronts, better to just ignore the medallions until you have power. Once you do that the medallions matter less anyway.
If they tried to fight head on legally they likely would have lost (since that's probably where the taxi companies are strongest and incentivized to spend all of their money to win at any cost).
In the case of Uber, their initial ignoring of the laws protecting Taxis I think was a good thing. Though this doesn't hold true for the things they were later accused of.