its easy , they kept the story which the first castlevania game started with ... ^^ so all the fans got interested and maybe you can ask the ooooold ooold old school fans like jorge and many peoples who played both metroidvanias and classicvanias
And what about people who played the three eras and liked those three? (as you said,
ask Jorge...) see,there's the flaw of your argument, you say LoS is not CV game.. for YOU, and quite a few people yes, but it could be said the same for whom SOTN and its children are not CV games.
And if anything, LoS is how an Old School vania (say, "true" castlevania) would look like in modern times. Linear, atmospheric, location-varied, slashing type, with a few puzzles here and there, oh, and big bosses, very big bosses.
(And no, SOTN doesn't have the
same story of old castlevanias, Dracula was Count Dracula alias Movie Dracula until 2003, there was no Vampire killer per se - it was a different whip each time, play Simon's Quest) also SOTN retconed plot points from ROB and Cv3 the same HoD to SQ. See? The story you "know and love" has been as constant as Dracula's look.
I've said it, and I'll said it again, LoS hate reasons are completely aesthetic. If it had less vibrnant colors, if Gabriel was an anrdorgenus pretty boy and if music was j-pop and "catchy", haters would be drooling all over it.
Sad, because CV was not like that until 1996.