This could be done to create problems for the Russia opposition party that may take over V.Putin. It is actually not important which exactly one, this answer assumes such party exists and is relatively pro-western.
The reason of damaging the pipeline then is to prevent the mentioned opposition party, when in power, from getting $200 million per day (source) after ending the war in Ukrainian terms. That much Russia used to earn from the gas exports. This really can be used to fix some problems with the economy. That much likely cannot be obtained just as a humanitarian or some other similar help.
Of course, EU may say "we do not want longer to have the dependence from Russian gas imports". But if gas purchases from Russia would be made the condition to end the war, may be possible to achieve opening Nord Stream 1 and 2, both ar full capacity. EU may opt to support the new government of Russia with money they need to pay for buying that gas somewhere anyway.
EU mostly wants safety first and would go great lengths to support pro-western government without ambitions to take over the sovereign countries around. How it used to be for some time in the recent past until somewhat after 2004 or about. Ok, there was not enough fame and living standards as they were. Without fame or without Nord Stream? Putin may have pre-made this difficult decision for his successors.