Around the turn of the century and before, there was no such sentiment. People just RE'd like it was completely natural, and in general weren't "afraid to read" what they had access to. As the saying goes, "no source, no problem." As a result, multiple alternative clients for IM and other services flourished.
There are these places near me where they just heap up a bunch of food. You can literally walk in, grab something to eat and walk out. Nobody will stop you. Yet people for some reason queue up to pay for the food. I believe this is what is wrong with the state of the world today.
Just to spell it out: read it as sarcasm. Do you just steal stuff unless they keep it under lock and key? If usually not what makes this case different?
Go to twitter.com in a browser.
This is just a different type of browser.
Physical analogies never work right with digital data.
To use an annoying analogy or two, take a penny leave a penny but someone shoves their hand in there and takes all of it.
It costs money to service requests and twitter et all make that money back through advertising and subscriptions. If someone uses an unauthorized API, it could use more than they've budgeted for.
Feels like a lot of RE'ing has piped down these days. The fact I can download Pidgin but none of the major proprietary clients I'd want to use on it have first party support only as third party plugins says it all imho. I miss the old days of MSN being easy to use on Linux and everyone else having it as well.