Agreed. I bought the 63cc Stihl 036 Pro with a 20" bar years ago, after reading more than once on various forums, that this was the best configuration any firewood cutter could ever want. I found the 20" bar was a bit much for it, when you have it buried past the nose in oak, but I was able to resolve that by installing some big cutting dogs that reduced exposed bar length to about 19". That seems to be about what that displacement can handle, again when burrying the thing into 30" oak rounds.
Then I started bringing home all this enormous stuff (ever cut a Ø60-inch white oak? I have!

), and realized 63cc was just too small, and started buying bigger saws. After a few swaps (084, 056 Mag, etc.), I eventually settled on the light and fast 85cc 064 AV as the ideal compliment to the 63cc 036 Pro. It's a winning combo, that I'd probably repeat again if buying today, with an MS 362 + MS 662 (since there's no MS 642).
If not dealing with huge stuff, I'd have to say those 63cc saws are indeed the ideal compromise between power and weight, and a great one-saw solution for most. If I ever sell this property and want to keep just one "all around" saw for cutting firewood or yard maintenance, it will probably be my 036.