I think this kind of approach to the question is a little bit of a problem. I don't really see what historical value anyone can get out of trying to quantitatively determine if the scale tips slightly more "aggressor" or "aggressed against." It also assumes that if we can agree on whether or not this falls on the plus or minus side of the ledger that we can settle once and for all the bigger question you asked - why is Russia viewed as an aggressor.

But the question of view is not necessarily easily answered even if we could come to a clean answer to your sub-question. When considering view you need to talk about geopolitics, you need to talk about political discourse (the Cold Warrior attitude still informs the way MANY people think about Russia in the west and if I had to give a short answer to your question, I would say that's probably it), and you need to talk about national interests, among other things.

So, Russia certainly was an empire in the 19th century, and historians generally say (with some amount of variance on definition) that the Soviet Union too was an empire or at least had elements that made it look like an empire (See Martin, Hirsch, Beissinger, etc). Historically speaking there is some precedent, but I don't think that really answers your question. The same can apply to most European countries, the United States, and dozens - if not more- of other countries too.

Therefore, the this ledger of aggression really doesn't answer the question because what we're talking about, at base, is a century of geopolitical conflict that is just behind us and did NOT end with the fall of the Berlin Wall or the disintegration of the Soviet Union. It didn't end with Yelstin and it certainly didn't end with Putin. It changed character, but the history that matters here has much less to do with empire and aggression and much more to do with the Cold War and its lingering political attitudes than historical "reality" of aggression (which is in and of itself incredibly difficult to define and can't be quantitatively evaluated the way your question presumes anyway.) The recent stuff in Ukraine and Crimea certainly violates the 20 year rule, but is might account for a more recent uptick in this sort of opinion, but it isn't something new at all.