If you want to know why Instagram turned off photos in Twitter with little warning, down to the precise second, just watch this GIF from Twitter's ad for its new photo filters, which even include a cropping tool to make artfully square photos.
I mean, there are a whole host of reasons that Instagram turned off its photos in Twitter — filters are certainly not the primary one! — but I wouldn't be surprised if the timing was at least a little bit pegged to Twitter's then-imminent launch of photo filters last week.