Hoenn is just not as interesting as the other regions.
How? It has a desert, an ocean, a volcano, a forest/jungle, and an ice cave.
Sinnoh was mainly Mountain. Kanto lacked any unique features aside from Mt. Moon, Rock Tunnel, and Seafoam Islands. Johto was better, but still most features were caves. Unova was better than all of those, but still isn't as diverse as Hoenn.
...Unless you mean lore, then I can see why that would be the case. Hoenn was bone-dry of lore outside of that one house in Pacifidlog that tells of the Regis, Mt. Pyre, and Magma/Aqua.
http://imgur.com/0MPQs "Everything ends eventually... and sometimes, you're not sure why." -Mazeka
My big problem with Gen 3 games is that towards the end of the game, there's nothing but ocean travel and water Pokémon battles. They get boring really quick. So then I have to train in Victory Cave for a while, because my only strong Pokémon is my Manectric. Also the starters can be disappointing. I actually haven't play much past Gen 3 though, I tried Platinum a couple times, but always get bored by badge 3... Are they better?