Hmm, I don't think the Class system has really gotten an opportunity to shine with the Job system yet. While perhaps not completely necessary to have, it does offer some good footing for areas like PvP, where classes that can customize itself more may be more beneficial than a Job which only excels in certain areas.

I "kind of" look at it as a talent tree from other MMO's. The Class System looks weird just because it really hasn't given you options yet.

I will try some examples:

I am a new Gladiator who just started the game. My weapons available to me are a sword+shield or a two-handed sword. I am given the option to focus on being a tank or become a DPS. That lv.1-30 area gives me the opportunity to decide which feeling or style of play I enjoy more. When I reach lv.30 I decide that I enjoy DPS more, which I decide to become a Dark Knight. What I also like is if I decide down the road I don't enjoy one role, I can start Paladin and see if that sparks for me.

WoW actually approaches classes like this also, not to the extent of FFXIV, but they do put you on a blank slate before choosing your role. Like if you are a Paladin in that game, the first ten levels gives you a little access to all roles you can become. Lv.10 comes around and then your talent tree is activated and you choose which role you prefer the most. Rather it be Retribution(DPS), Holy(Healing), or Protection(Tanking). You are given the option within a class.

FFXIV does almost the same exact thing as I said above. Perhaps to more of a extreme level, but I do get the purpose of keeping the Class system intact. They have already said in the past that Classes will still have it's advantages. My guess mostly is on the PvP side like I said above. Assuming you can still use abilities of other classes. It does actually sound clunky in a balance sense, but I guess we will see how they decide to approach it.

tl;dr: The Class system can work, it just needs time to flourish itself.