I mean the logic is obvious. If you are popular enough you want to keep the platform exclusive. If you aren't then it makes sense to go multi-platform.
BlackBerry thought their platform was strong enough and BBM would pull everyone else in. They were of course wrong.
It seems like Apple is strong enough to keep iMessage useful even if it is platform limited, and surely some people are buying iPhones for the status-symbol of Green Bubbles (or Blue, I can't remember I don't use iMessage).
Of course every platform wants to think they are strong enough to pull this trick, admitting otherwise is very difficult. Of course by the time it is obvious that you aren't strong enough it is probably too late.
Funny Blackberry story. The .jobs top level domain was launched around the time RIM was really struggling. .jobs was one of the first gtlds that wasn't .net, .com or .edu. The management team at RIM wanted a .jobs domain for their career website. They didn't buy "Blackberry dot jobs" they bought... the other one. The company I worked for provided career website software. The meeting where we tried to explain why RIM and .jobs was a bad idea was a classic.
I hate the conspiracy theory that Apple did it intentionally to make iPhone users hate Android. The original iPhone had all green bubbles. The blue was only to differentiate.
Of course they are, but Apple loves status symbols. To a large extent they are a fashion company as well as a tech company. For example the constantly rotating design or Animoji. (only available on the expensive model of course!)
BlackBerry thought their platform was strong enough and BBM would pull everyone else in. They were of course wrong.
It seems like Apple is strong enough to keep iMessage useful even if it is platform limited, and surely some people are buying iPhones for the status-symbol of Green Bubbles (or Blue, I can't remember I don't use iMessage).
Of course every platform wants to think they are strong enough to pull this trick, admitting otherwise is very difficult. Of course by the time it is obvious that you aren't strong enough it is probably too late.