LaTeX tables are generally very tight. You can play with \arraystretch but in this case (different font sizes for different rows) it may not be very easy.
Two packages can tackle this problem, each with its own limitations:
cellspace defines minimal distances between cell contents and the row above or the row below. All you have to do is define these minimal distances, and prefix the relevant columns specifiers with the letter S (or C if you use siunitx).
makecell can add vertical spacing at the top and bottom of cells. You have to set this spacing, then use the command \makegapedcells.
Another solution is to give up all vertical rules, to have a more professional looking table, and replace \hline\s and\clines with the\toprule, \midrule, \cmidrule and \bottomrule commands from booktabs, which introduces somme vertical padding around these rules.
Here are examples of these solutions. You'll find more details in the documentations of the packages:
\documentclass{article}
\usepackage{cellspace}
\setlength\cellspacetoplimit{5pt}
\setlength\cellspacebottomlimit{5pt}
\usepackage{makecell}
\setcellgapes{5pt}
\usepackage{booktabs}
\pagestyle{empty}
\newcommand{\mycoordinates}
{
\vspace{0.2cm}
\begin{tabular}{|Sc|Sl|} \hline
\Huge Point & \Huge Original \(\rightarrow\) Transformed \\ \hline
\Huge A & \\ \hline
B & \\ \hline
C & \\ \hline
\end{tabular}
}
\begin{document}
\mycoordinates
\vskip 1cm
{\makegapedcells
\begin{tabular}{|c|l|} \hline
\Huge Point & \Huge Original \(\rightarrow\) Transformed \\ \hline
\Huge A & \\ \hline
B & \\ \hline
C & \\ \hline
\end{tabular}}
\vskip 1cm
\begin{tabular}{cl} \toprule
\Huge Point & \Huge Original \(\rightarrow\) Transformed \\
\midrule
\Huge A & \\
\midrule
B & \\
\midrule
C & \\
\bottomrule
\end{tabular}
\end{document}

\extrarowheightor seebooktabsormakecellor add additional spacing manually at the end of the row or ... ? – cfr Oct 04 '16 at 22:33tabular's default NOT give enough space to the contents of the cell? Even in row B and C of the picture, there is more space underneath the text than above. Why? And is there some place I can learn all of these defaults? – WeCanLearnAnything Oct 04 '16 at 22:43\strutso the space below is the normal depth to make room for\normalsizedescenders, the fact that the capital letters are closer to the top than that is just a feature of the font design and the baseline spacing chosen to go with it, essentially (without the\hline) you would see the same spacing in paragraph text – David Carlisle Oct 04 '16 at 22:47booktabs's manual which has quite a lot to say about this in general, even if not in particular. – cfr Oct 04 '16 at 22:49%from ends of lines in your definition. – David Carlisle Oct 04 '16 at 22:50