Aries was not a transitional champion.He held the title for 5-6 months and it became the ROH WORLD championship while he held it.
No, Joe defended it internationally first.
But Aries reign was fantastic. Nearly 6 months of almost non-stop defenses around the world, and the buildup to his eventual loss was logically done (his neck being battered on for over a month leading to Punk taking him out with a Pepsi Plunge).
I honestly see no reason why putting the belt on a guy to get him to the next level is a bad thing. Most people go to ROH to see the whole product, not due to simply the champion. Aries' win over Joe was brilliant BECAUSE it felt so out of nowhere, and Aries wasn't seen just yet as a true headliner. So what's the next step? Have Aries' storyline be that he's hellbent on proving his win over Joe wasn't a fluke, so he goes crazy, accepting every single challenge thrown his way for nearly six months...which leads to his downfall.
And again, ROH is going to sell out the Manhattan Center regardless of whether Danielson is the champion, or if, say, Rocky Romero is the champion. Besides, you can't look at all title reigns and reasons for certain guys holding titles the same: to me, it's a sign of smart booking if each one is treated differently.
Homicide, Low Ki and Punk had stories of "run towards destiny", Aries was the out of nowhere shocker, Xavier was the chicken**** heel, Joe and Morishima used it as launching pads to build up their monster characters, etc. etc. If belts are given out using the same parameters for each champ, things get dull.
As for where Morishima ranks, that's a tough call. Joe and Danielson are obviously on top, and Aries' reign is far too often overlooked for how solid and engaging it was. I'd put Morishima at maybe #5; I loved his character, loved a lot of his matches, and I typically enjoy well crafted monster title reigns, but the fact is that time constraints restricted THAT much from being done with him in the time he had it (i.e. NOAH wasn't about to keep him coming back to America for two straight years or something ridiculous).
That said, random thought, but while I dug that Morishima was a loner tweener who needed nobody's help, he always struck me as a guy who, in ye olden tymes, would've been absolute gold if paired with a manager like Bobby Heenan. The heel manager would talk him up, put over how brutal he is, but then the minute he hit the ring, the manager would just stand back, afraid that, in the heat of battle, his monster might turn around and eat HIM.
One last note: Xavier's reign was much better than it gets credit for. Going back and watching some of those defenses from '02-'03, he played his part very well, and the matches against him helped bump Paul London up to a whole other level.