Sometimes is easier to check the (partial) result of some node in a workflow in Excel. Now the only way is to export the table with Excel writer or copy the entire table from the output data window (I do not know other options, if exist please let me know).
It is possible to upgrade the output data window that will be possible copy the entire table (with headers) with one click (so I can paste it in Excel) or export the entire table (with headers) to Excel or save the entire table (with headers) to Excel.
so I have checked and ticket for copying the entire table with headers included (internal reference: AP-13584) is done and will be part of KNIME 4.2 release - usually summer. This can already be check with KNIME nightly build version.
There is also ticket for filtering output data (Excel like filter) and I have given it +1 for you.