Not sure where you're getting this top 10-15 % figure for the 11 star bonus, but that is completely wrong so far as I know. It's not even close to being the top 10-15%. The 11 star bonus is officially relegated to "high legend" players and I know players that consistently finish in the top 500-1k for standard NA legend that do not receive it, as well as players that have finished below 400 in wild NA legend and not received it. Bear in mind that the top 1,000 players in legend in either format represent less than 1 percent of the player base actively participating in said formats, at least if the statistics we've been provided by Blizz in the past are anything to go by. There is no way in hell that 10-15 % of all players in either standard or wild are top 1k legend. Now I have heard of people with extremely high MMR retaining an 11 star bonus after consistently ending the month very high in legend (top 10-top 100) and then taking it easy for a few months, but they still had to achieve very high legend to get it in the first place. If you have some sort of evidence of players receiving the 11 star bonus despite having never achieved high legend, as well as a reputable source for this random 10-15 % figure, I would be very interested to see those. Otherwise all of the information we've been provided to date by Blizzard suggests that the 11 star bonus is strictly for players that end the month in "high legend" (at least sub 500 in NA in either bracket from what I've been told), which is a sub one percent fraction of players on ladder in each respective region.
600 legend here (wild). Never have gotten more than 10 stars
If you find it too easy, why not challenge yourself a bit then?
Instead of using a braindead method of netdecking top wr deck and then playing it over and over again till you're bored to death, why not create your own unique deck and try to hit legend with it? I guarantee it to you it will be a super fun experience and even if you don't manage to hit legend with it, you won't feel sad and you certainly won't be complaining about it.
Journey is what brings us happiness, not the destination.
This. The journey is the fun. I found the same to be true for WOW, leveling was more fun than end game
You have to consider that you also have been playing at a higher level than most players for a few seasons so it's easier for you to get back there. Star bonuses are a great, otherwise most people wouldn't do the bullshit grind.
D5 to Legend is where it takes longer but again you are used to playing at a high level. Maybe try new decks you aren't good with