Microsoft enters every line of business in which somebody is making money selling software or computing services.
The providers of TCP/IP network connectivity (cable, phone, etc.) are all angry that other companies and getting very rich using their networks and seek to extract some of that value through "traffic shaping", content blocking, and all other sorts of chicanery that spawned the idea of network neutrality.
Twitter exists to make money. They see third parties making money selling licenses to enhanced clients, so they decide to get into that market. twitter client developers proved the market for them. Now the investors, who want a big return on their money must insist that Twitter follow the money into those markets. Its Twitters platform, and Twitter's data.
I sympathize with the developers, but the general public (decidedly self-absorbed, and apathetic towards the issues affecting developers) do not care whether twitter turns the thumb screws on their third party developers. The End users are no longer the internet cognoscenti, and they just don't care, as long as they can tweet.