It's not whether there are more bad movies now than there were then. It's more HOW the movies are bad and WHY they're bad. And then the way that Hollywood goes about selling the public those movies.
Of course there was crap back in the old days, and there was mediocre or workmanlike stuff that people don't remember because it's overshadowed by the classics. Call it the Salieri Effect if you want.
What I've seen, though, is a far, far more calculated, formulaic approach to marketing and branding of movies nowadays, used to cloak the crap. Here's two examples.
1.) Red Dawn (2012) -- this film is entirely generic, and isn't particularly well done. It's just an invasion movie with some teens acting as partisans. If they put it under a different title, say "American Partisans" or whatever, and changed the names of the characters, people would refer to it as "That crappy Red Dawn ripoff." Why? Because it's not a very well done film (which is not to say that the original is exactly a cinematic masterpiece, of course). But, Hollywood knows that just the story and the actors alone isn't going to be attractive enough to bring people in to watch it. Ergo, they slap the "Red Dawn" title on it, give the kids the same names as the characters from the original, and kick it out the door. Now, it didn't end up doing well, but I expect that this was their calculus.
2.) G.I. Joe: The Rise of Cobra (2009). This film is GARBAGE. It's got awful acting, a boring and uncharismatic cast (with a handful of exceptions), and a really, really stupid story. Strip out all name references to the G.I. Joe franchise but leave EVERYTHING ELSE the same, and what do you have? A big-FX crapstraviganza that probably would've flopped. And when you watch the film, aside from those names and such, there's basically NOTHING that has anything to do with the original storyline from the toys, cartoons, or comics of the original franchise. If it was "U.S. Commandos" and the main good guy was named "Spike" instead of "Duke" and the main badguys were called "Arthur LeMarche" and "ZODIAC Overlord" instead of "Destro" and "Cobra Commander", the movie would've made a paltry sum at the box office. But you dress a dude up like Snake Eyes, and give everyone the right names....and now you've got box office boffo.
It's all just a contemptuous attempt to manipulate the audience -- and it works. And they KNOW it works, which is why they keep doing it. THAT, in my opinion, is what has changed. It's the way in which films are marketed, rather than how many good vs. bad films there are. The great triumph of modern Hollywood is in making boatloads of cash from BAD movies.