This is just my opinion if you disagree state why so.
Reasons DPPt sucked:
1) The 4th Gen Pokemon are the most rush and uncreative
2) The Physical-Special split
3) The story line with Team Galactic and such was too over the top
4) The Gym Leaders and E4 were way too easy
5) The Sinnoh region doesn't have many Water routes
DPP wasnt that bad.
1) Its the same with the third generation - they created handful of cool Pokemon, and a hundred of 'Dunsparces'. Some of them are really cool - the starters, Garchomp, Giratina, Dusknoir... - while most are simply retarded - we seriously didnt need things like Lopunny, Pachirisu...
2) You must keep in mind how the game changed from gen to gen. The RBY to GSC transition was huge, with the addition of many new game mechanics and held items, which leaded the game to a Stall-ish pace. GSC to RSE improved the customization and training with EV's and natures, and with more powerful stat-up moves (namely Dragon Dance and Calm Mind), which made the game pace a bit faster; however, Balance and Stall were still a bit more succesful in RSE than pure offense.
DPP needed something to differentiate it from the previous generations, and what did so was the physical/special split. Allied with powerful offensive Pokemon (and with Platinum's widespread powerful moves), this made Offense much more viable (and perhaps more rewarding) in DPP than it was before. So I dont think it was bad - it made DPP unique, and I liked that.
3) It's not like Team Magma/Team Aqua had reasonable storylines either xD
4) But that's what the rematches are for (on Plat, at least). I do think the rematches were well level'ed, allowing for some good late game training.
And if you think about it, Johto had the easiest Elite 4 ever. (yet the coolest one)
5) This one I gotta agree with. Not like Hoenn, though (Hoenn was the worst region imo), but it sure needed mre of those. Maybe they could have added a Surf-able path near Fullmoon/Newmoon/Iron Islands or something. Thankfully, Johto and Kanto have enough of those, so I'm looking for HG/SS.