As far as I know, MND does not help your Bar-spells. MND will give -you- a boost to your Magic Defense Bonus, but I have never seen it carry over to any party members. The only ways I know of to enhance the effects of your barspells on other party members are through Enhancing Magic Skill, Barspell Merits, and equipment with Barspell Enhancements, such as the Blessed Briault. MND will impact your Cure V potency, and help you to cap lower level cure spells faster, but Equipment with Cure Potency Boosts seem to do far more than most MND-based equipment. MND is mainly beneficial for Stoneskin and your own Magic Defense Bonus; Cure Potency is a lesser benefit, and the only other thing I can think of that would be of use to a whm. RDMs and WHMs get some use out of it for Enfeebling Spells, but by end-game, most WHMs won't be enfeebling unless they are working in a solo or duo setting.
And the whole thing with n00by mages is, well, not really new. It's been a problem since I started playing a year and a half ago, and continues to be a problem today. The only thing I have encountered that may be considered an increase in the problem, is a declining willingness of mages I have met to listen to advice. RDMs who can't refresh, BRDs who can't elegy or requim, WHMs who can't haste or regen, BLMs who don't understand what a Magic Burst is, SMNs who don't know that any command besides 'Assault' exists in their pet menus.
Then again, there's also the NINs who never bothered to buy any ninjitsu besides Utsusemi, the PLDs who don't understand why they should use Provoke more than once a fight, the RNGs who don't want to was ammo pulling, then use Barrage and EES while the mnk pulls, and wonder why they die, the DRGs that won't get rid of their 'DEATH FROM ABOVE!!!! OMG YOU D13 N0\/\/z!!1111one11! JUMP!!!' macros, the SAMs who don't understand what a Skillchain is, the DRKs who complain when they use Berserk, Souleater, and Last Resort on the same WS, then die, the THFs who use SATA 32 seconds before there's actually a mob at camp, the WARs that insist they can tank as well as a NIN, the MNKs that insist on getting CH 6 with 100 Fists when the WHM has 24 MP, and the BSTs who enjoy MPKing random parties just because they happen to be getting fast exp.
So yeah. Coming from a melee standpoint, I can totally see where a bad mage would stand out, and cause you grief. But coming from a mage standpoint, I will personally vouch that it goes both ways. XD