There are definitely people in your same shoes who like video games but don't want to engage with this part of the culture. I personally love E3 and Giantbomb's coverage of it, it's my favorite time of the year; although, there are also comic fans/movie fans/whatever who just do not enjoy the conventions and fanfare of big reveal events. They just want to enjoy the end product whenever it's available, and that's fine.
I don't think it's immature of people to get hyped about these events, but I understand that over time some things just don't excite you in the ways they used to. If you want to enjoy video games, but not associate with this part of them then go for it. Do what makes you happy, and the people who love E3 are going to be doing the same and there's nothing wrong with that or them for doing so. And if you are looking for a game related experience that doesn't revolve around just sitting at home watching trailers, there's always PAX!