Nice breakdown Axelefekt , I largely agree with your observations. That said, I thought Zarainia did a pretty good job in a tough matchup. Sometimes in a match like that, even if you're well-versed in strafing/LOS, you still don't have the time (or inclination) to perform in a textbook manner - because you're too busy thinking ahead and/or taking risks. You're doing things you either can't afford to do in a close match, or don't need to do when your own team is clearly superior.
Sprig: for a ridiculously long time I didn't strafe either. Like you, I knew about it, but couldn't be bothered to use it. I still did OK. Wasn't until I watched a few top players methodically dissecting my team that I finally decided to buckle down and get used to strafing. It did take practice, but I finally got the hang of it, and I'm glad I did. Inevitably, there are going to be situations you cannot survive (and shots you cannot take) without strafing. I suggest making a conscious effort to do it a little bit in every match. Eventually, it will become second nature. And you'll be better off for it.
On the other hand, not using ion is something I absolutely cannot identify with, lol. I actually use ion a bit less now than in the past - early on, sometimes it was all I used. My motto was "MOAR ION". Probably (in part) because I got a kick out of preposterous damage numbers. When you're preparing to engage in a GS duel, often one solid opening ion hit is all you'll need to guarantee victory. And nailing a scout frequently leaves them dead in the water (or close enough). imo, ion rail is the single best weapon in the game ("best" is certainly debatable, but it's damn good by any measure). Maybe try to spread the ion love a little more frequently.