I agree with the OP, and I don’t think it’s immature at all. I think it’s more a matter of wanting to get credit for having the foresight to like something pre-popularity. Let me give you two examples:
LOTR. I read it back in '84, again in '91, and again in '96. I LIKED Tom Bombadil. And I read through the “boring” parts three times. In 3 feet of snow. Uphill. Both ways. And I liked it, dammit! Not to mention that I read all of the other texts, studied the materials, and RPGed the hell out of that world. I knew it intimately. When the movies came out, that was great, but it was really annoying to have people assume that all I knew was the movies, and assuming that I, too, skipped over the “boring” parts of the book. I want credit for my hard work, dammit!
There’s another side to this: Over the past fifty years, a number of artists have offered up their interpretations of Tolkien’s work. And some of it was really great art. It was not uncommon to walk into a bookstore and see books and calendars chock full of this artwork. Now? PJ’s work has crowded out all competition. It’s become the “official” interpretation of LOTR. It’s sad to see so much good work pushed aside in favor of the popular stuff.
My second example is a little less arty.
My mother is one of the most creative housekeepers I know. She’s very handy with a glue gun. And she can make the simplest of household items a thing of beauty. (And taste. We’re not glittered toilet plungers here.) Visiting her house, which I’m doing next week, is astonishing. Very clever, very creative. But in the mid-nineties, her friends commented on her stuff saying “Oh, you got that from Martha Stewart, didn’t you?” No, you lunkhead. She thought it up herself.
In fact, I have been something of a victim of MS’s popularity myself. My ex-girlfriend was a MS freak. A total devotee. On one show, MS was explaining how to make gravy. She said not to put the flour directly into the hot liquid, but rather suspend it in a cold slurry first. That way, no lumps. “Wow, only Martha Stewart would come up with something like that!” exclaimed my GF. Actually, sweetie pie, I’ve been doing that for at least a decade. Housewives knew that trick for many many years. MS is just taking the credit for it.
On one MS show, she demonstrated how to make leaves out of chocolate. Once again, my GF was astonished at her ingenuity. I was compelled to point out that not only was I doing that years before, but that I had served said chocolate leaves to said GF. Man, talk about not getting credit!
Is wanting to get credit for something like that immature? Possibly, but if you think so, then that makes you a poopyhead.