I think some games definitely aren't worth the price they're asking, but others use some pretty impressive new engines with top-notch graphics and mechanics. For example, Uncharted. That is a crazy price tag, but it looks amazing. Comparing them to previous ones are huge... and I realize they're all on older consoles, but still... it still looks a lot better then some of the other current stuff out right now. And if a game as a multiplayer mode, it gives a person to keep playing it for a while. So if you're likely to do that it's kind if worth it because you wont just trade it in later.
There are a lot of great little indie games that are much more reasonably priced, super good, and pretty fun! I played one called Rain that was about a little boy who saw a girl being chased by a demon through the city... but it's in this dream state, I guess you'd say. So he's running through the city trying to find and help her, but they're invisible unless they're in the rain. It's short (and I'll admit I got it free with PS+). There is also Never Alone, which has this really beautiful and interesting storyline. It's rich with folklore and stuff from a particular group in Alaska, and you unlock all these little videos that tell you about it. There is also The Unfinished Swan, which basically has you going through a colorless world (initially) armed with paintballs that helps you expose the environment. Eventually shadows come into it, and the paintballs become water balloons to help plants grow and such... it's an interesting concept and I really liked it. There are some other indies that are throwback to old school games like Rogue Legacy and Shovel Knight.
But more than anything I think companies just keep churning out sequels and such because they know people will throw all kinds of money to have them. Like Assassin's Creed. They come out too close together and sometimes they're so glitchy. I haven't played most of them because I feel like all the ones I have were so alike it wasn't worth it, and according to what I've read they didn't really make the continued storylines conclusive. At least the first ones. At this point I think it's just money grubbing.