I'd wager that for every person who thinks TTS is a good thing there are about 5 others who can't stand it. It just happens that the person who decides on settings is one of the former but if you were to do a poll about it, I'm sure the truth will be revealed.
I can't actually remember the last time I even saw TTS implemented on any software, game or otherwise. Isn't it primarily just used for disabilities? What I'm trying to say is that there is a reason nobody ever uses it, it's incredibly annoying and can easily be trolled by spamming in chat.
Also, why assume that every player is an English speaker? There are regularly games played between random nubs in locked games who are all Germans or Russians and every one of them probably has to go through process of finding and disabling this stupid setting, just like the rest of playerbase.