So something that requires knowledge is either something that you need to be skilled at, or its something that is just bad? That last part makes no sense. Requiring knowledge is a good thing, it doesnt make a thing bad.
The Centurions are high skill floor tanks, that require thought to play. They require you to actually learn about your tank. Other lines outshine them as pure medium tanks, sure, because the Centurions arent pure medium tanks. Also the speed "buff" doesnt actually change that. Other lines will STILL outshine the Centurions as pure mediums in 9.17.1. The tanks arent being changed in a meaningful way.
Heres what will happen though, if these speed buffs go through:
Players will play their Centurions like pure medium tanks using their new "speed" to try and flank other tanks or wolfpack with other mediums. They'll put their tank into a bad position and then they wont be able to get out of it, because they wont have the DPM and they wont have the armor and they'll be as big as a barn. They'll die, and then they'll come to the forums and whine the the tank is still bad, despite them having put themselves in a bad position, in a tank that never should have been in the position in the first place. And then people will complain that the 50kph top speed is either too slow or that the tank needs a better power to weight or better terrain resistances, when all the tank needed from the get go was better DPM and better gun handling. And we'll be right back here in another year and a half having this same conversation, because buffing the speed of the Centurions/4202 isnt how you fix the Centurions/4202.
Talking about two kinds of tanks.
Good tanks that have high skill floors that average to bad players won't be able to be effective in.
Bad tanks that are just bad.
You say the centurions are good, but have high skill floors. That may all well be true. You are a better player than me. I did "OK" in them, but suffered from another issue... a lack of roles being filled on the front line. Unless I'm wrong, Centurions are support tanks (the CAX may be something more, but I'm not focusing on tier 10, just the 8 and 9). Support tanks in the average pub arena suffer when the front line tanks aren't filling the role of front line tanks. This has happened so many times to me that I just try not to play support tanks as much.
I totally agree with speed buffs, the new Centurions will rush out and suffer even more because they are closer, but still don't have much armor, comparably less dpm (7/1) and/or alpha (Cent 1) AND they are big as barns. So yeah. This buff may actually hurt the line even more, at least on how they are handled.