“wasn’t a bad name” is the understatement of the year. it was one of the most successful brand names ever. normal people with functioning brains would kill to have a brand that’s so ingrained in the language, especially without the threat of genericizing the trademark.
xerox didn’t want people to use xerox as a generic verb to mean photocopy, or kleenex the same for a generic tissue.
but Twitter was never used to mean another social media site, and tweeting never means posting on Facebook or Tumblr or whatever. a tweet is specifically a post on Twitter. that’s the perfect brand.