Generally speaking, the WoW style MMOs aim to have the DPS classes well within a margin of 5% of each other. There will always simply be the best class at any one time, fixed with minute tuning. The classes in these design paradigms usually bring something else or maintain some sort of unique utility that makes them superior in certain situations.

So long as the lowball DPS are capable of clearing the content, then it's fine. The rest is just peen measurement.

Samurai is no more out of place now than it would have been in the early eras of the Themepark MMO. It deals more personal dps but brings very little that bolsters everyone else, while the rest are all well within an acceptable margin while also bringing in utility that far outweighs the amount you lose. If it were a matter of raw numbers, then we'd only ever have melee groups, and while it is still possible that Stormblood raids will allow for this, it's doubtful the paradigm has shifted that much.