hey guys, I'm not really known in whole mapping/modding community, am just a no-name who likes watching beatmap threads and following the ranking process -- I have been observing this whole discussion for awhile now and there are a couple things I think are worth pointing out-
A lot of the reason why mappers like hi-mei and kisses are pushing back so hard against ranked meme mapping is that they feel (with good reason) that this is a very slippery slope and by allowing worse and worse songs like ha ha ru ru getting ranked, it lowers the bar for everyone else and eventually the entire game goes spiraling into degeneracy, with their own hard work spent creating quality maps, getting cluttered out by a flood of nonsense memes and metronome maps filling the ranked section.
But, historically this is not the case... if you go back for a moment and play over some meme maps from 7 or 8 years ago, i.e. internet pack vol. 1-2 (which were deemed worthy of having their own achievement on player profile), you will find yourself suffering through horrible 2010 meme songs, combined with horrible 2010 meme mapsets. it's really painful to play for us today, but that was the standard of achievement-worthy ranked mapping back in those days. Line that up side by side with the memes of today, choco cookie, number one, nico nico douga, octagon collaboration, etc... you will find the standard of meme mapping has gone up significantly over the past several years, along with the quality collectively of all ranked mapping, and the standards continue to rise.
The beatmap nominators and quality assurance team do take their job seriously, and they are doing very well at providing quality content for the entire osu! community... by simply allowing meme songs to be included in ranked mapsets, you aren't likely to allow the mapping and modding ecosystem to collapse. rather, I would say, go ahead and allow mappers to use meme songs in their mapsets, and continue to hold their work to the same 2018 mapping standards that you hold for everyone else.
at the end of the day, it isn't so much about making everyone map a single genre of music. it's about letting the community choose their music, and making sure they map it well.