As I have stated before, I only really use my cures when my WHM has informed me they won't be curing me for whatever reason. The "MP issue" i'm stating is merely in comparison to GLA - all of PLD's self-sustainability moves (aside from Aegis Boon, which both GLA and PLD get) require MP. GLA on the other hand has plenty of different moves that don't require MP, and can also recover it itself. I did mention the uselessness of PLD having cures (in the current state they are in) in my 3rd point.
As Riaayo mentions (and I mentioned in point 3), PLD curing itself now suffers from good WHMs. Due to it's low HP and lack of damage reduction, PLD essentially needs to be topped off frequently. This is the primary role of the healer, so it's no surprise when you go to cast Holy Succor (especially noticeable with it's longer casting time) on yourself and cure for 0. I like some of Riaayo's suggestions, and thought that addition to FFXI was fairly solid.
My point here is that all this adds up to switching from GLA to PLD loses some key utility moves (free heal, force evade, etc) and gains healing magic which is rendered nearly useless under normal circumstances. Sure, succor is meant for others, but for me at least, the WHM typically just cures others before I can as well (and everyone has a way of curing themselves at this point).
You mention Cover and Divine Veil. Personally, the use of cover is very limited as I've haven't had many issues with hate that a Provoke/Flash couldn't fix (aside from having a WAR in the party). It has been mentioned by other posters as well that cover is essentially useless right now (someone mentioned they used it on great buffalo, someone responded saying provoke just got hate back fine). Divine Veil is utter garbage. WHM already gets regen, and while this stacks with it, it relies on a somewhat clunky predictive system where you need to be guessing that the WHM will cure you soon, and that you'll be taking damage after that (I tried it in Ifrit - after having the WHM trigger it, Ifrit starts running around). The suggestion that it hits others around the PLD often in regular end-game party play actually means it only hits the PLD (it's quite rare for others to be near them - look at the distance difference from just the front of Ifrit to the back of Ifrit, for example).
I would argue GLA can protect others just as well as PLD, if not better. GLA can protect itself, and can use cure more often than a PLD can due to MP recovery. Even if the GLA is just healing itself, the enmity over time and freedom that gives to a WHM contributes to overall party security. PLD get's nothing in terms of enmity generation over GLA, which I would have actually understood (sacrificing survivability for being able to hold hate that much better to make up for WAR's epicness).
You mention BRD - as I keep addressing (and did in my OP) GLA can have a BRD in it's pt as well. This GLA is less reliant on one song (ballad) and could perhaps request a different one (DD power for more enmity, regen to make things easier) if they can't find a use for the extra MP. I would say reliance on a specific job should not be "working as intended". As I've said before, parties already rely on having to find a WHM and a tank (I really hope WAR tanking doesn't get nerfed, but PLD tanking gets buffed) - I personally don't want to also HAVE to find a BRD for everything I do.
In my opinion, for things short of the equivalent of HNM and longer "farming" type events (as in things like Dynamis in FFXI) I don't think BRD should be required. BRD in most cases should be a boost that speeds things up and makes everything go smoother. Since GLA and PLD can do almost the same thing (personally I feel as though the abilities PLD loses are better than the ones it gains for tanking anyway), and PLD needs a BRD where GLA would benefit from but not rely on a BRD.