Many of those Pokémon were crap when introduced. Absol had 130 Attack but nothing to use it with until 4th gen. And Altaria used to be a completely forgettable Pokémon with an interesting design but it was the weakest Dragon in the game so it totally sucked.
There are a few nice ideas in 3rd gen Pokémon's design but a lot of the new ones from that gen were forgettable weaklings, like Delcatty, Masquerain and the lovable Heart Scale fodder, Luvdisc. Also, many inferior copies of older Pokémon (Mightyena, Manectric, Aggron, Walrein, the early bugs...).
You should play the games to have a better opinion, though. I find them dreary today because 4th gen is such vastly superior for battling, but they were the first ones in the "reformulated" Pokémon so a couple rough edges can be excused. The music is hit and miss depending on how much the trumpets were used. The map past Lilycove has a lot of water and convoluted hidden areas, which explorers admire but I'm not so fond of. :P
Make sure you play Emerald, though. Ruby and Sapphire are completely disposable.