On one hand the differences between 1 and 2E are about the same as 5 and 5.5 and that was a whole new edition.
It's also akin to the changes of 3.0 and 3.5 which they labeled a half-edition. Also like 5 and 5.5 this was done to not scare people off and to make more $.
Either way this could have been called 6E or 5.5E and both would be correct.
What it is NOT is "still 5E".
Me, I'll go with 5.5 because 6E won't pop up for another 10 years give or take. And it IS coming just like this half ed was though people didn't want to believe it.