Yes, those annexations were of great value in frustrating the German advances on Leningrad and Moscow in 1941. This is not directly relevant to Russia's current policies, but preventing extension of NATO into Ukraine is greatly to the advantage of peace and stability in Europe.
Formations of army group north reached the outskirts of Leningrad about 9 weeks into the campaign, I believe. Rather quick for the distances involved. Additionally, army group center had it's issues around Smolensk or so and was nowhere near the baltic states.
The losses inflicted on army group north weren't yet really significant during it's drive up to Leningrad. Plus, pretty much on the first day of the war, uprisings began in those baltic states tying down soviet foces as well in significant numbers. I don't really think commanders were already frustrated with the campaing at that point. So strategically and tactically, the anexation of those states wasn't really the point that made the soviets come out on top in the end.
Even if all that was part of Stalin's plan to bring the SU to a position were it could eventually engage in and win a major war against it's ideological (arch)rivals in europe, simply anexing other nations as puffers isn't what we should embrace.
And with that we come back to the main issue here.
The idea of large/powerfull states being the only actually soveraign ones due to their military capability, and therefore having the right to command the fate of smaller nations to ones own ends, is basicly pre WWI thinking.
The consensus, I think I can say, has been that at least throughout Europe we managed to move past that after WWII, or definitely in 1990 for the whole continent. That has pretty much been the center principle around which the european reconciliation and order has been built.
President Putin, essentially bringing back these preWW1 believes in diplomacy and statesmanship (what his rehabilitaion of the Molotv-Ribbentrop pact comes down to), is going against everything that is at the center of peace and stability in Europe for decades now.
On a side note, it wasn't really NATO aggressively expanding eastbound by forcing others to accept membership. It was those eastern european states deliberatly and repeatedly asking for membership. And not by corrupt and bribed rulers doing it against the will of the people. All of this brought those states even closer together, which I would say is enhancing peace and stability, not degrading it.
The only issue then is Russia bullying around against that. Now if all those former eastern block states decide for themselves to turn away from Russia and towards NATO, maybe it's up to Russia to ask herself what might be the reason. And CIA mind controll probably isn't the answer.
So in the end, who are you, or I, or Russia to tell those nations which organizations they may join or not?