Locking down the OS is actually just good business.
Look, I don't know how to put this but... I have a nice setup with my Droid, with a beastly OC, all the bloatware removed, and with many interesting apps that people here would probably find very useful... but when I run into someone on the street, the #1 question about my phone is: "Holy crap! When you move the phone, the lady's breasts giggle! How can I make my phone do that?!" I'm not exaggerating either, the other night I was playing a little pool in the bar, while like 4 girls huddled around my phone taking turns shaking it.
That's the audience they design the devices for. Not us. The "OMG, they wiggle!, I need to buy a Droid now!" idiot general public.