Hi,
For logical and safety reasons, and for compatibility with Microsoft
Excel, I suggest that:
* The Sort Option "Range contains column labels" be_unticked by
default.
Your suggestion does *not* establish compatibility with Microsoft
Excel. Excel tries to *guess* whether the first row of your
selection has to be sorted or not, by checking for significant
differences between the first row and the subsequent rows in data
type and/or formatting.
Try yourself in Excel:
Z
1
3
A
2
will disappoint your expectations, as well. 
It is good that LibreOffice has this option, but a beginner don't
know that option and will sort what he/she has selected, and it is
frustrating to see that the first column is not sorted at all,
thinking it's a bug (like I did).
When sorting, it´s not recommended to select a range, rather than a
single cell. Calc (or Excel) will select the range to be sorted by
its own. Selecting a specific range before sorting is only helpful
for very special cases, when automatic selection fails.
FYI: RTFM and study the rule
"For sorting, filtering, or using the Pivot Table, always select
only one cell."
on page no. 4 of this official manual:
https://wiki.documentfoundation.org/images/6/69/CG4108-PivotTables.pdf
Unfortunately, the chapter of the manual, that specifically deals
with sorting, does not mention this rule. :-/
Cheers,
Stefan