Yeah, this. The trouble with evasion tanks is if they are 100% effective, they are broken (which do you prefer, a standard tank that takes reduced damage or an evasion tank that takes NO damage? No contest), and if they are not 100% effective - well, the rest of the time they die (which do you prefer, a standard tank that takes reduced damage, or an evasion tank that randomly dies from time to time? Again, no contest).
NIN were broken the first way in FFXI for a long, long time. Then SE started adding bosses with attacks that ignored shadows, and they became broken the other way.
NIN in their heyday were AWESOME, and that's why folks remember evasion tanking fondly - but the problem was that they were TOO GOOD. It was very difficult to design encounters able to challenge a party with a good NIN tank. SE eventually gave up and wrote NIN off, designing encounters that only a damage reducing tank like PLD could field, and that pretty much marked the end of NIN tanking in FFXI. I doubt they'll make the mistake again of bringing evasion tanks back into play.
In regards to the original post, I, too, think that the roles should be swapped around. I favor BLU as DPS, DNC as healer, and GEO as tank. I do want to point out, though, that the odds of us getting all three jobs next expansion are slim; doing three for Heavensward just about killed the dev team (and landed us with MCH being underdeveloped, practically a clone of BRD), and that's why we only got two jobs with Stormblood.
