Because there were a lot of little threads left hanging at the end of season 1 that a jump will just leave hanging, meaning the lines and time and set up were just wasting everyone's time. (The stalker, Tyler's escape, Bianca and her mother, Enid finally being a "real" part of her pack and how that "welcome" would go, the fallout of the reveal of the Nightshades, the impact of it on Enid and Ajax's relationship specifically, Wednesday's latest manuscript being done with her self imposed publication deadline).
If season 2 addressed those things, including the whole stalker thing from the end of s1, as a "next semester" thing and didn't have a pile of wait and sees and then s3 did a time jump to Wednesday off to uni then I wouldn't mind a jump. But they did all this set up for s2 and now they're just going to skip two years just because?