I'll go as far as to say the Ruthless Aggression era was better than the Attitude era, simply because the wrestling was better and it didn't feel like an overkill plethora of kneejerk reactions to whatever WCW was doing. And vice versa for that matter, which is what ended up doing them in. I think by about 2006 or so however it kind of dawned on the creative that they're doing more than they really need to, most of the roster on high salary were expendable, and could just settle on matches that were well-worked rather than book wrestlers that actually had a believable chance of winning. IIRC Finlay, yes, Finlay was booked in three PPV main events in a row by the end of the year.
That, IMO, was the beginning of Supercena, because of the unprecedented cash cow that was the Spinner belt (I loved it as much as much as the next guy at first, but it should have never of come back after his first reign), he ended up in angles that avoided pitting him in a title match for 3 months, or was eventually booked against no-hopers like Umaga. Rumor has it that after Taker won the rumble in 2007, he was originally scripted to jump to Raw and win the WWE title at Mania, but wanted to bring back the Undisputed design.. I'm sure everyone can figure out why that never materialized, and even at the time it seemed weird to me that he went for the WHC despite how many times he held the former.
So from there on out, it was like he was booked in decent matches with HBK, Orton, Bobby Lashley etc. but none of them were ever gonna be put over because of the "hurpity-derp, the Spinner belt would look strange on them!" logic. At the time I guess the creative were still sincere enough to realize how distastefully stale this was getting and banked HUGE on the Vince Mcmahon death angle, and a lot huger than alot of people I think, but it was cut short by Chris Benoit actually dying, there's no way that shit would've flown with the thoroughly respected perception of Benoit at the time, LBSH, if you had pick a bunch of wrestlers likely to a have a breakdown like that over a single weekend, he wouldn't have been on anyone's list.
I think if the circumstances were made clear immediately and before the WWE aired further programming instead of airing a tribute show out of gut instinct leaving them with egg on their faces, they might have handled it more rationally and professionally rather than being salty at the fact he left them with bad publicity and pretty much single-handedly forced them to abandon what could've been the biggest stunt since the Montreal Screwjob.
So with that, they're pretty much forced to.. push Cena. On top of having held it for a year, had enough and actually suffered a legit injury, no ifs and buts about it, he had to vacate the title. And the creative having no choice at the time but to push Orton, admit defeat and keep the Spinner belt anyway.
After that it was a slow but sure transition into a PG product, and TNA became too obsessed with the prospect of signing up overworked talent for the sheer novelty.
I didn't mean to ramble on and reminisce like I did, there's still been plenty more ups and downs in between, I just feel like all of the above is what shaped it into the sack of shit it is today.