As long as character designs aren't low quality, i.e. unfinished designs and just horribly drawn, then I'm fine with it. Multiple characters already looked "lame" to you, but you didn't mind because that's how they always were. Just because characters that looked "okay" before look "lame" now, doesn't mean Kishi's manga is going to shit. (At least that isn't the reason)
Character designs aren't as important of an aspect as you may think. Gon from Hxh looks "lame" to me, but is still a great character. Gintama characters honestly look "lame" to me, but I still watch that 24/7 because it's amazing. Most characters from Steins;Gate looked lame, but I enjoyed it because of the story.