Twitter CEO Dick Costolo in an interview on WSJ.com:
In its events push, Mr. Costolo said Twitter is vying to “more closely tie the shared experience on Twitter to the actual event that is happening.” As Twitter burnishes its platform, Mr. Costolo added that Twitter also wants to move away from companies that “build off of Twitter, to a world where people build into Twitter.”
There you have it. Because of the chosen ad based business model Twitter is moving from an offsite integration to onsite integration. If they go cracking down on clients from third parties and other apps they will almost certainly lose their prime position in the web ecosystem. Good for everyone else as Twitter had for a long time the almost sole attention of indie web developers looking for a web platform to build off on.
That is bad for Twitters long term outlook but the investors, who at this point almost certainly are the driving force behind the companys moves, are probably eyeing an IPO that comes right after the first big ad successes in numbers and before the probable meltdown of Twitters usage.
Interestingly Twitters biggest competitor Facebook is earning most of its revenues with advertisement but doesn’t seem to have a problem with offsite integration from Open Graph to clients.