Idea: if you're very interested in promoting veganism or vegitarianism, help make it taste better, or invest in or donate to those who are helping make it taste better. As my other much-downvoted comment showed, I am very skeptical that appeals to altruism will have nearly as much of an affect as appeals to self-interest, especially outside of this community. I believe most people eat meat because it just tastes better than their alternatives.

Grown crops are far more efficient to produce than livestock, so there are plenty of other good reasons to transition away from the use of livestock in agriculture. If steak were made to "grow on trees", why pay all that extra for the real thing? If you lower the cost of vegetarianism by improving taste, more people will adopt it. If they don't adopt it they'll still be more likely to forgo meats for vegetarian dishes if those dishes taste better.

In the case of low-quality meats (e.g. McDonalds) the taste bar isn't even set very high.

When I first decided to be a vegetarian, I simply switched from tasty hamburgers to tasty veggieburgers and there was no problem at all.

I think your sample size might have lead you astray here. My personal experience is exactly the opposite. That said, I looked for studies of meat vs. faux meat taste and didn't find anything. I wonder if a love of meat over alternatives is innate or is learned, and if there exist vegetarian recipes which really do taste as good as the real thing.