Lots of factors drive changes in a language. New technologies is a key factor nowadays. Laziness, in a way, accounts for some changes too, contractions being a prime example. But sometimes fear does it too.
I've been noticing the last few years an overwhelming number of otherwise intelligent people who use "more" instead of adding "-er" to a word. For instance, I've heard "more clean" instead of cleaner, "more firm" instead of firmer, and even "more funny" instead of funnier. I've also seen these kinds of phrases in printed media, from ads to blogs to newspapers and magazines. And don't even get me started on the number of news anchors and other TV personalities who do the same thing when speaking off the cuff.
It seems that people have become so reluctant to take a crack at the correct -er word that they automatically shift to the more construct. Do these people not read? Did they attend lousy schools? Did they have teachers who didn't know the difference themselves? Or did they, as I think might be the case, struggle with learning the -er words and, on top of that, have teachers and parents who corrected them so often that they just gave up, deciding to use the more construct, regardless of what they think the correct one is?
I don't know, but I'm wondering whether this observation is an indication of a shift in our language toward the more construct in all cases. Hmmmm.