What if one just manually add the times to your SQL query?

I have been doing something like this:

" WHERE DATEFIELD BETWEEN " & @DATE1 & " 00:00:00" & " AND " & @DATE2 & " 23:59:59.997"

I know this works (please ignore any typos or syntax errors - I have not checked it), and I know it uses the indexes.

Why would something like this not be advisable?

regards

Dawid