I've got no hate for the later generations.
Yeah, the exponential increase in the apparent power of the mons is a bit irksome, since it moves the plot from a light-hearted and pretty straight-forward game about catching and training monsters to fight for your amusement and profit into something more climactic and dramatic, but that's the way it goes.
I'll admit, I always had more fun preparing for the first few dungeons, when I'm catching relatively low-level creatures, training them, ect. than before things get really intense and you start getting mons which have the power of tiny, and not-so-tiny, gods.
But, I do have the nostalgia, and I simply preferred having fewer monsters to keep track of. It always worked better, I thought, to have a relatively small number of monsters, enough that if you spend the time, you can actually know all of them. At one point, I knew all of the original 150, with types, usual attacks, and where to find them. Once it went to 250, it was almost impossible for me to casually pick it all up, and by the time we got up to the current god knows how many, it's simply impossible.
I thought 150 was enough variety to keep it interesting, but not so much that it becomes "I have to have an encyclopedia open to make this feasible"