English Bows get an extra bonus, the vanilla one has 25% I believe.
Problem with the early longbows is that they skew the power ratio a lot in favour of defence, up until then it is fairly even. Flanking only helps if you measure success by not losing units which is kind of silly because why then attack in the first place

Now if knights had a bonus against archery units and the bows lost their heavy cav. bonus .. would make bows less useful as the omni-tool they are (defence and offence with the same unit) and necessitate building some of the good old Guisarmier which are not appearing at all now - thanks to bows.
"Nerfing" them is counter productive as the 'issue' only appeared because they were moved up in the tech tree .. a lot I might add as there are some hefty pre-reqs for Military Tradition which were also skipped.
due to the previous pre-reqs I almost never built longbowmen, why?
musketmen are better and weren't that far away, build arquebusiers and upgrade them to musketmen was usually the way to go in my games (cost less hammers)
admitted I don't play aggressive, so I seldomly research military techs anyway
it's about negating first strikes from bowmen, not about the withdrawl chance so much which is why I chose
Flanking II
I concider it a necessity if the bowman I intend to attack even has
Drill upgrades
but the 'silly not losing unit' part has a serious advantage..
attack with mounted seargents first(immune to first strikes anyway and a high withdrawl rate), then send in the heavy cavalry
the mounted sergeants that managed to withdraw(up to 70% chance or so)
most likely damaged a unit and yet live to fight another battle..
even a longbow with 0.1 strength can do serious damage due to its first strike(s)
the same can't be said for a knight i.e. with 0.1 strength
if you're referring to how hard it is to attack say Paris with Knights..
last time I attacked (England beta 8) it took 5 min for the french to finish attacking me once I dow and moved my units to bombard Paris.
I'm guessing they attacked with 30+ units
I still lost half of my 15 Knights when I took the city.(took more that one turn, too many units in Paris)
But worth it imo, I was opposed by Longbowmen which is why I mention it.
The only units that manage scare me with Knights are Ghazi, Paladins and Teutonic Knights (ok and pikemen/landsknecht, line infantry)
Besides any other suicidal acts against Polearm units
Maybe that Hungarian UU too, but I don't think I've encountered them