oh hey im late too brother
i map mainly for expression, and for the songs i love.
as of now, i'm mainly mapping one artist (though i guess im beginning to open up to other artists now). the artist uses themes which i appreciate, and i try to incorporate them into my mapping. for instance, their latest album laments on the practice of literary and musical plagiarism. i express this by looking at the famous maps when osu! gained popularity such as Highscore, a few modern maps, a few graveyard maps, and a few of my own maps. i copy ideas from those maps and blatantly copy then into the maps of the album.
i've done this two other times (one is a double-album with references of my own accross mapsets, and the other is a loosely selected set of beatmaps which try to relive my experience as a player by replicating styles from 2 years ago, but that last one is still pretty fresh with just one song on the list) but all of them are incomplete, because i cannot push myself.
this looks so self gratifying of a post hahah... if it comes across like that, nothing i can do to change your mind
anyway, that's my idea of expression. it's reliant on reference and context, so i doubt if all of them become appreciated, more so for the same reasons. also, i don't strictly implement this as i sound. i'd say it's an expression for mappers rather than for players. actually, maybe it's all just for myself.