The thing you have to remember is that it kind of was always the way it is now. I am always surprised that people have such short memories. I mean if you really think about it, the merchandizing should have devalued the first film more than a couple of crappy sequels. Look at Rocky! Rocky would have been seen differently without sequels but people still separate them and the original and call the original a classic. And right from day one, Star Wars had all the junk attached to it.
In the 1970s you had:
-Toys! Everywhere! Toys for characters you hardly even remembered! Except at first there were no toys. There were toy boxes. Lucasfilm came up with the greatest scam any company ever devised: THEY SOLD KIDS FUCKING EMPTY BOXES. FOR CHRISTMAS.
-R2D2 cookie jars. Yeah, they are charming and cool. But it kind of shows that every conceivable product was Star Wars-ized. There was princess Leia shampoo. Wookie underwear. THE SELLOUTS!
-Maeco Star Wars disco remix. On vinyl single, or as part of a greater SW-themed disco album. I have both, but sadly no disco ball or bellbottom pants. When this was new it was at least hip, now its both pathetic AND uncool. Star Wars disco music. Just say that again to yourself. There was Star Wars disco music. And people danced to it.
-TV specials! Back when there was only four channels and you were practically forced to watch this crap. R2D2 and C3P0 having boring banter while they address the audience on how Star Wars was made? So, are they in the movie or are they acknowledging that they are actors who made a movie? Or are they supposing that it's a movie that used two real robots? You get about 10 minutes of worthwhile content in this one-hour snoozefest that has only become valuable because of nostalgia.
-THE HOLIDAY SPECIAL. No commentary is required here. FUCKING. HOLIDAY. SPECIAL.
-"Pay money to join the Star Wars fanclub! You get a two-page promotional 'newsletter' and an iron-on patch all for the equivalent of $40 dollars today!"
So, you see, it has always been like this. And that was just 1977-1978. All that happened in the first two years. The reason being?
Star Wars was meant as a light-hearted fun romp for kids and kids-at-heart. It was fun having a princess Leia shampoo. Then a decade later it become mythologized and everyone forgot what it was like in 1977 and all the crap they put out. Then they proceed to complain endlessly each time there is a new Star Wars pencil set instead of just ignoring it because it will be forgotten in another twenty years. I know that's not the focus here. But my point is that the "devaluation" of the series has been there from the beginning. And if the Holiday Special and wookie underwear can't devalue Star Wars then Jar Jar Binks certainly can't. In the long run, I mean.
It's a vicious cycle. :p