If these are so good, why aren't governments and anti-smoking groups supporting them?

We do not know for sure. There does not seem to be a concerted effort to block these products in most countries, though that remains a possibility. Regulatory agencies have a legitimate responsibility to help make sure the products are pure and contain what they say. This creates a challenge in the current environment. Groups that are truly anti-smoking should embrace any alternative, but those that are more interested in making life difficult for smokers or nicotine users do not like these products because they could make nicotine users more comfortable.

Whenever government regulatory agencies are confronted with a new product, they need to find the proper category to put it into, and then make sure it complies with the standards associated with that category. In this case, even though nicotine is widely available in many forms, it is still important to make sure the products do not contain any hidden toxins, that they function properly (e.g., cannot accidentally deliver an overdose), and so forth. In this case, the waters have been muddied by the claims that it helps people quit smoking. Whether or not it does is not the concern of the agency, but when such a claim is made, the claim needs to be proven (and that means more than anecdotes).

In some sense, the situation is absurd because someone could much more easily introduce another harmful product that was part of an already established category than introduce a new and obviously safer alternative. Governments typically worry more about hypothetical new risks than clear old risks.

Some commentators have suggested that governments are so used to tax revenues that if electronic cigarettes became more popular they could threaten this income. This is not an absurd concern, given the current economic conditions and given that governments have been raising tobacco taxes to make up shortfalls in other areas. We can only hope that if that is the plan, that they keep the taxes lower than on tobacco products because the last thing you want to do is make people choose traditional cigarettes because they are cheaper.