What makes you think that nobody is questioning it? I'm sure some people are, but the fact that informed consumers are purchasing these cars speaks for itself.
Of course, even being informed isn't going to help if this sort of poorly secured connectivity becomes the norm for new vehicles, which seems to be happening disturbingly quickly. If you rely on the independence offered by having a car but all cars have similar dangers, you might have only bad alternatives to choose between, but they're still bad.
[Edit: That last sentence was ambiguous. My intended meaning was that the alternatives to using a car at all might also be bad, for example incurring significant costs and disruption moving to live somewhere with viable public transport instead.]
1) The features provided by Tesla extend far beyond those provided by "cloud-enablement"; the fact that "informed consumers" are buying the cars does not indicate that their purchasing decision came down to isolating cloud-enablement relative to cloud-features.
2) Your hypothetical informed consumers don't really exist, unless the only people buying cloud-enabled cars are computer scientists.
2) Ever looked at a tech company parking lot in South Bay? A lot of people with CS background are buying the Model S. Not all buyers are computer scientists but informed buyers most definitely do exist.