All of your tastes change over time. If you keep eating/drinking something over and over and over again (without it making you sick), you will begin to find it acceptable.
I think the assumption that everyone who doesn't like green tea doesn't like it because the flavor isn't strong enough for them is a bit much. Out of all the people I know who don't like gree tea, not one finds the flavor too weak.
There are many reasons why someone might not like green tea:
1. They have only had experience with low quality or improperly-brewed greens.
2. They don't drink anything except water & a particular soda, and even then only cold (no hot drinks).
3. They don't like the "green" flavor. This is the single biggest reason I encounter.
As for me, I love both blacks and whites, but can't stand green. Specifically, I don't like tea that tastes like grass or hay, no matter how fresh. And, incidentally, although I will drink a frappacino slushy when required in social situations (because the sugar, milk, & ice covers up the nasty coffee flavor), I have never liked coffee.
And it certainly has nothing to do with not liking change. I enjoyed that pu-erh tou cha that tasted like putting a spoonful of dirt in my mouth. And I don't think there is anything quite as unique as deciding that you like something that literally tastes like dirt.
One has to assume that there must be a reason why so many people in the west don't like the taste of hay/grass, while so many in the east do.
I, for one, think it has everything to do with what people are raised on. In the west, we really don't have anything that we eat which tastes like grass. And our parents don't feed us green tea as we are growing up. So we don't get used to it as children. It goes back to that second sentence:
"If you keep eating/drinking something over and over and over again, you will begin to find it acceptable."
You do this as a kid because your parents make you.
Side note: Two of my friends had parents who never made them eat anything. One likes literally nothing other than katsup, bread, cheese, and orange soda. The other likes meats & starches, but no vegetables. Mark this, parents: you should make your kids eat their vegetables, because they will eventually begin to like them. Not every vegetable (they could dislike them due to allergies), but at least make them pick 2 or 3 green vegetables that they will eat.
As an adult, however, there is no one making you eat something you don't like. So, unless you have a really good reason to do it to yourself, it's just not going to happen.
A lot of the people I talk to who like green tea are the same people who made themselves eat other grassy things (like wheat grass juice) for their health. So, they've adjusted to the flavor of grass.
To me, grass is something my chinchillas (and other livestock) eat. I'm sure I could learn to like green tea if I drank enough of it. But why would I do that? What possible motivation could I have for doing it? I love so many different teas. Why would I drink one I don't like?
P.S. It might also have something to do with the fact that I'm allergic to grass & hay. So I may have an instinctual avoidance towards anything that reminds me of it. Considering how many people in the west have allergies to these things, it makes me wonder if maybe that is a big reason why a lot of people have such a strong negative reaction to it.
P.P.S. I do think it will change. As green tea becomes more popular in the west, and people are exposed to it at young ages, I believe we will see fewer people who hate it.