This article argues an alternative (maybe even complementary) view regarding the cause of the Russian invasion of Ukraine:
(..) Russia’s security concerns are in fact genuine, and NATO expansion eastward is seen by Russians as directed against their country. Putin has been clear for many years that if continued, the expansion would likely be met with serious resistance by the Russians, even with military action.
In this regard, when NATO leaders reiterated the decision taken at the 2008 Bucharest summit that Ukraine would become a member of the Alliance with the MAP as an integral part of the process and Ukraine's right to determine its future and foreign policy, the likelihood of Russia issuing a military response increased.
According to this answer, besides quite a few disadvantages (inflation, nuclear war risk, etc.), the US might eventually benefit from the war, despite the short-term issues and risks. However, I cannot see why the European NATO members risked a military escalation in Ukraine.
Turkey blocking (or delaying) Finland and Sweden’s accession to NATO is an example of how easy one NATO member can place a roadblock on one another's country joining NATO. I guess that it would have taken only two or three important members (e.g. Germany and France) to oppose supporting Ukraine's ascension to NATO in order for June 2021 Brussels summit declaration to sound very differently.
My question is basically what's in it for the European NATO members to support Ukraine's accession to NATO? In the short term, there seem to be important negative consequences.
To make my question more specific, I am asking why did European NATO members agree with Ukraine's accession to NATO, as per point 69 in the Brussels Summit Communiqué?
We reiterate the decision made at the 2008 Bucharest Summit that Ukraine will become a member of the Alliance with the Membership Action Plan (MAP) as an integral part of the process;