I have a guess as to why we see a ton of generalist champs that have come out in the last 2 seasons

It is because Riot has bought in, whole-sale, into the player made meta, which they are now quasi-enforcing, and are creating champs that fit into the positions of said meta.

IE; New champs is going to be a support, mage, tank-support, marksmen, etc.

Which is why most of these new champs are generalists; they cover almost all of the said bases of their position, and need to do so in order to create a desire for players to get them.

Meanwhile, most of the older champs were created with no meta to stick to, which is why so many of them are specialists. was the first real jungler, but he was only really a jungle champ because his sustain is top-notch. is a very strong duelist, but he can do other things. used to be one of the best ganking junglers ever, but they nerfed his clear time because he is such a CC machine that they felt that his presence in jungle was too much for the current metagame. But outside of CC and peels, does nothing. His heals are small, his damage is lacking. If cannot find a target, he will die because he cannot sustain himself.

IMO, we need Riot to forget about making champs that fit into a certain position incredibly well, and instead focus on making champs that do great at 1-2 things but are lacking in other categories. Whenever balance Reds talk to us, they talk about "clear, defined strengths and weaknesses." Yet they then give birth to champs who have no true defining strength but have no weaknesses at all; they are great or at least above average in every category but have 0 weaknesses for their enemies to sight in on and take advantage of