They bring up FFXI because:

Final Fantasy XI:
Developer(s): Square Product Development Division 3 (pre-April 1, 2003)
Square Enix Product Development Division 3
Final Fantasy XIV:
Developer(s): Square Enix Product Development Division 3
They've created 2 successful MMOs prior to XIV, including another Final Fantasy title, which had all of the basics as well as 10 years worth of experience including content creation -- This is why people bring up FFXI but it doesn't mean people want a FFXI-2 when people say Square should have taken what worked from XI and incorporated it into XIV. Making a -2 would FFX > FFX-2, which took place in the same world, same people, same storyline but it also added a lot of new features and refined the battle system.

I've only seen a couple of people say XIV shouldn't have jump because XI didn't..I've seen a lot more say it shouldn't because the game doesn't need it currently nor would it solve problems by just adding it.