I agree! I wish they were the other way around or at least both of them acted the same because I cant really imagine kai acting like the playboy type

Generally at some point in time of the fandom being established, there'll be some generalisations about pairings and personalities. And yeah, there'll definitely be different opinions for all of the pairings.

Sehun is usually read as the girlier one (or the girl in the relationship) in sekai mainly because of:
1) his height (used to be shorter than Jongin during the height of their popularity)
2) aegyo (does it willingly, showing that he's 'cute' and more 'feminine/submissive' in a way since it's normally stereotyped to be girls who do aegyo rather than the other way around)
3) his skin (it's paler than Jongin's which kind of makes him seem more delicate—his skin would be comparable to Snow White and other traditional princesses etc etc, plus it allows for the stereotype that he would be not very outdoorsy or active—just because his skin is less tan)
4) his slight lisp (often written as a flaw, plays up to the poor boy stereotype, allowing fics where Jongin stops the bullies and such)
I could go on more but...

(Personally I find bottom Jongin more appealing, though it's more of a preference than anything, actually. Plus, it's rare to find them nowadays so it's sort of like a treat I guess. Not that I have anything against bottom Sehun, I'm fine with anything.)

Well for once i really like that cliche (sehun as the fragile one and kai as the wild one). Maybe bcs i stan them since 2013 when sehun was shorter and 'girlier' than jongin. And that image still there in my mind so i tend to read them as what they used to.

I should agree with you in some point like some writers dont write something new. But its not really new in this place. For example: we can always find new arrangement marriage fic every day. Or kingka and the nerd. Or the head of mafia group and the innocent person. Or person trapped in a house (or apartment) with a group of handsome boys.

And maybe thats the characteristic of each otps? Like hunhan, where sehun is the cold guy. Or kaisoo where kai is the cold mysterious guy(?) Its been so long since i read those otps fic so pardon me if i generalized them in the wrong way.

What is it im rambling lol. I just wanna say my opinion. No hard feeling tho.

omgosh o_o i kinda agree tbh and i hate that image of jongin. i think hes more like the cute boy-next-door type tbh so i write him like that :3 and sehun isnt like that creys

Not really, it could also be the other way around. I personally like bottom Jongin and there are fics where Jongin's the omega