Hmm, so they did, now that I look closer at it. Guess it was so that they don't confuse the newer fans who never played the X games.
And that was so wrong in the first place.
"They don't like to bother the new players, but us the fanbase without any merci for logical thinking humans."
What kind of hypocrisey is that?!
And what I more hate is that stupid Praire in ZX. She can't even say for crying out loud Ciel's name. Why being so extra vague in the story, when other games are mentioned in Area N, which actually handle that backstory?
IMO they shouldn't care about all those clueless newbies. It is their own problem, not that of the developers.
In fact, such fanservice might even rise the selling of the older Rockman games.
Edit:
@Hypershell
Who says that his Z-Buster in X7,X8 and CM malfunctioned?
It could just have been the case, that Zero just prefer close combat, instead of ranged combat or Capcom just not wanted to do it because of the gameplay balance.