I am confused by a few things here.
-
Champion GG lists WW win rate at the 49% like Op listed for Plat +. But on the page for WW Plat + if you look at his win rate breakdown by #games played he is listed at the lowest as 51.6% for 1-50 games played. His win % is only above that in every other tracked division, 51 to 100, 101 to 150, 151 to 200, and 201+ he only has a higher win % and at no point is under 50%. Seems a bit weird that his averaged win % would be under 50% when his win % in every tracked player experience has him above 50%. I guess this is caused by patch being tracked as well as season totals? Well regardless if you look at his win% by patch its not till .5 you see him drop below 50%, and he only does this at plat and higher. WW still sitting pretty in bronze to gold.
-
Why your using Plat + to judge "easy to play".
Like not only is plat + a small, small , minority % of the players its also going to be a MMR where the expectation is the playerbase has a strong grasp of all the games mechanics. So your sample size of # of players is small and they inherently have some advantages when learning new champions.
Meanwhile in bronze to gold MMR WW tends to have 99% of his players tracked as 50 games or less and enjoys 50% or higher win%.
Like, Plat + is listed as 3,042 matches, this Vs 41,399 Matches tracked from standard mmr .( This is just by patch btw, the #s by tier are Bronze 16,534. Silver 12925 Gold 11940, at time of posting)
Of the games in standard MMRs you find that 99% of the WW players have 50 or less games yet all of them are 50% or above win.
So looks like of a massive majority of the players who represent the average level of skill WW is doing just fine with a very smooth learning curve.