I think there are two pretty good reasons that Twitter moved away from being an open platform, and they are: 1) ensuring a good user experience, and 2) making money.
The tweetstorming thing, for example, conveniences particular writers at the expense of all the other writers (and quite a number of readers). I hate it, and will unfollow anybody who does it regularly. It's the tragedy of the commons for an attention economy. Twitter's demand that people be concise is a large part of its value to readers. The more they control the UI, the easier it is to nudge people in particular directions that shape good user experiences.
But that's a small thing next to making money. To experiment with various ad products, they need extremely fine grained control of and reporting on user experience, and they need to be able to rapidly change that as they come up with new ideas. That's hard enough even when they control everything; getting a zillion developers to do that is impossible.
Focusing on the core was great, but nobody was paying them for the core. They're spending ~$1.5 billion/year. Anybody who says, "Twitter should do X" without explaining how their plan will help pay the bills is not going to get a lot of consideration at Twitter HQ.
Re: I get where you are coming from. However, people use services differently. Twitter has failed in determining how services should be used.
Re: Annoying Tweetstorming.
People should be able to mute content from certain apps. Just like you can silence your Candy Crushers.
Re: Making Money.
On a sarcastic note, "I'll think of a way if I am paid 6 figures a year" :). But seriously, we are making content more valuable by adding more people to its service. Twitter can retain the rights to serve ads on those third party services while sharing some of the ad revenue.
The tweetstorming thing, for example, conveniences particular writers at the expense of all the other writers (and quite a number of readers). I hate it, and will unfollow anybody who does it regularly. It's the tragedy of the commons for an attention economy. Twitter's demand that people be concise is a large part of its value to readers. The more they control the UI, the easier it is to nudge people in particular directions that shape good user experiences.
But that's a small thing next to making money. To experiment with various ad products, they need extremely fine grained control of and reporting on user experience, and they need to be able to rapidly change that as they come up with new ideas. That's hard enough even when they control everything; getting a zillion developers to do that is impossible.
Focusing on the core was great, but nobody was paying them for the core. They're spending ~$1.5 billion/year. Anybody who says, "Twitter should do X" without explaining how their plan will help pay the bills is not going to get a lot of consideration at Twitter HQ.