2. You can go to places like bricklink.com to buy almost any block or set that you want.
3. Branded sets usually mean more specialized pieces which only increase the source material you have to draw from when building things.
4. Lego also puts out stuff like this: http://www.eurobricks.com/forum/index.php?showtopic=67132. Highly specialized pieces that aren't tied to a brand.
When I was a kid I would have been in heaven if they had all of the sets out there today. Buying a Harry Potter set wouldn't have meant that I can only play Harry Potter[1]. It would have meant that I had more legos to combine in other ways with the rest of my parts (all sets ended up broken down and stored in a huge bin of Legos). I realize that ultra-specialized pieces like 3-CPO or R2D2 minifigs can't really be reused elsewhere, but most specialized pieces tend to be pretty generic (e.g. Harry Potter wands don't have to only be used with Harry Potter).
[1]: Example, I recently saw a Harry Potter set that used a combination of a translucent 1x1 brick and brown stud to create 'potion bottles.' It's a pretty generic idea that translates elsewhere.
I don't know whether I ever came up with a decent solution back then, but I do know that trying to come up with one was an excellent exercise, one that I probably would never have embarked on if I'd had the pieces they make today.
edit: grammar fix
As others have stated, Lego was in trouble before adopting the franchise sets. Would it be better if Lego was 'pure,' but out of business? It's not like they removed the ability to do what you're talking about, they just added new things. You could easily limit yourself, or your children, from using the new things.
The problem was no one bought general Lego blocks. This is still the trend today.
I guess not many people remember, but Lego was in deep financial trouble during the 90s and early 2000's. Until they started creating licensed packages and video games based on 3rd party franchises like Star Wars, Lego wasn't selling anything.
Highly branded sets probably push children more into playing roles and sticking to, probably still imaginative enough, scenarios rather than into creative process of building.
They basically look the same; http://www.brickset.com/brickLists/?5954
Also, pirates was a dead theme until PotC came around.
I would estimate at 40% as good as logo. Which puts it down in the play with it a bit and then ignore 'while the cat (or hoover) eats it' camp.
Kid-me deduced that the more generic sets had more pieces, so in an early attempt at cost optimization I leaned generic the few times I had money. Though, it was also cool to get some sets with interesting pieces that let me branch out. Vanilla bricks can be limiting at times.
For instance: http://www.amazon.com/LEGO-Bricks-More-Builders-Tomorrow/dp/...
However, I realize it's working out for Lego, and if the licensing is what's necessary to keep them going, then I'm not faulting them too much.
http://kingdoms.lego.com/en-us/default.aspx?icmp=COUSFR33Kin...
And this fancy castle?
Now, a way to organize these...
If they don't know it exists, they're less likely to want it.