Reasoning of 'x' and 'X' key

[EmiOnGit]

I'm not questioning the general usefulness of selecting the line below
however after playing with helix for some quite time I feel like

• 'x' = extend_line_down
• 'X' = extend_line_up

would make a lot more sense as the default compared to the
current default:

• 'x'=extend_line_below
• 'X'=extend_to_line_bounds

reason of extend_line_up

Currently extend_line_up is not bound by default which is a command I often need.
Especially when selecting to many lines by mistake or when I want to expand the selection in both direction (in combination with 'alt+;')
On the flip side the current default, extend_to_line_bounds, I barely use whatsoever (enlighten me how you use it personally).

reason of extend_line_down

The reasoning why I believe this would make a bit more sense is because it seems to provide more functionality.
It enables removing the highest selected line (again in combination with 'alt+;').

Overall I'm just curious if there is any good reasons you might come up with that would justify the current default :)