> Finland mattered because of its perch above the Baltic Sea and because its southeastern border with the Soviet Union was less than 20 miles from Leningrad. If the Germans took Finland, they would be dangerously close to this Red Army stronghold.
Just substitute Russia for "the Soviet Union", NATO for "the Germans".
Meanwhile (because of another weird fluke of Napoleonic wars), soon after the loss of Finland, one of Napoleon's capable generals (Bernadotte) was given the crown of Sweden. As a Swedish monarch who had no attachments to the lost territory and possessed the strategic acumen to realize how awesome deal it was not to have Finland around, he did not contest the conquest (plus, he could use it as a point in Congress of Vienna to negotiate Norway to be given for Sweden as "reparations"). Why it was such an amazing deal? For several hundred years, area of Finland used to be a battlefield for numerous wars fought between Sweden and Russia. Ever since Napoleon and the establishment of the buffer country called "Finland", Sweden has enjoyed a remarkably long period of uninterrupted peace.
During same period of time, Finland's history could be summarized as "Finnish people not being fond of the Russian ideas how to deal with the defense of St. Petersburg". I don't foresee this state of affairs changing anytime soon.
There is no geopolitical reason to invade Finland and there is also no economical reason to do so. Most companies are foreign owned and would be pulled out of Finland the moment an invasion would start. The main natural resource of Finland is trees, which Russia has more than plenty of. Adding Finland to Russia simply solves no problem whatsoever, perceived or real.
Finns ignore this. They're paranoid because their parents taught them to, whose parents taught them to until you reach turtles.