Adobe says they made a purposeful change to Illustrator's Text Selection features. What do you think? Feature change or a unintended bug/change?

I suspect most users never use a forced line break, or know much about it.
So this illogical change in text selection to skip over selection just a line and jumps to a whole paragraph will never be seen. Doubt there was a user Feature request to change this also.

Illustrator 2018 changed how text is selected with triple clicks and using UP/Down Arrows.

A simple return/enter is a ^p, paragraph return.

A Shift-Return is a ^n, forced line break.
^n, ^p are commonly used to search for hidden formatting characters, like ^t for a tab.

One click is a Point, Two Clicks is a Word, Three clicks was Sentence.
Been that way since Illustrator 1.
Other programs have four and five click features to expand text selection from just a line to a paragraph or story. (inDesign/Quark/Word)

Now Three click, ignores forced line breaks, and selects text from Paragraph Return to Paragraph Return.

Note that Illustrator's search/replace feature only sees a forced line break, which is now ignored when selecting text. Just a hint that this change was not intentional to skip over a natural progression of selecting text.

Down Arrow text selection has changed also,

Just a down arrow goes to the same point in the line below.

Command Down arrow use to select text to the end of the line, ^p or ^n.
Now, Command Down ignores any ^n, forced line breaks and goes to the next ^p, paragraph return, not the end of the line.

Why the fuss?

Searching to replace tabs from long lists to change them to line breaks. Illustrator's Search/Replace function sees and has a short cut for a ^n Forced Line Break. It does not understand ^p as a Paragraph Return, nor has a shortcut to that formatting charter.

You Can "copy" the hidden paragraph return, and paste it in the field. It shows as a blank.