To add to this comment, the majority of Finland's infantry fighting and transport vehicles that in use are still Soviet BMPs and MTLBs. Same applies to artillery and also all light machine guns are and probably will Russian PKMs for a while.

But yeah since the fall of USSR they've been slowing shifting towards buying from NATO countries/allies, with German Leopard tanks having replaced T-72s and recently buying artillery units from South Korea.

Another upside:

- Making it clear that you're not in the 'other guys' camp.

A NATO Finland would have been incredibly threatening to the Soviet Union. A friendly, non-aligned Finland that just wants to be independent, without stepping on anyone's toes is a useful buffer state.

After the second world war, Finland had to tread very, very carefully.

Finland is not a member of NATO and it does not have any foreign army on its territory so it can make a decision based on technical characteristics and economical (not political) factors.

Stopping a major combined arms invasion from an easterly neighbor is the focus of all of Germany's big training exercises to this day. Instead of whatever the Heer says through its public affairs officers, look at what is actually being practiced and paid for with the Euros in the defense budget. It's not counterinsurgency, it's not disaster relief, it's training out of Wildflecken focused on stopping a theoretical invader from penetrating the Fulda Gap with tanks.

The German military in 2017 could probably not stop an invasion by Canada. NATO on the other hand, most certainly exists to deter Russian aggression.