I got to disagree with your reasoning, Character choice is still just that, there are people out there that still prefer Del over Baird, and even Kat over Del and Baird. Each character is different, and each in a sense unique to each other. There will be no need to spam Barriers once is is sorted, and to be completely truthful, spamming Barriers is not the right thing to do, it never has been, i personally consider it a selfish thing to do, just like Sentry spamming. The Engineer is a support character, and regardless what The Coalition says, the Engineer can be Offence, Defence or Support, they are incorrect, and i will stand by this decision with absolutism, the Engineer is a Support character, should be and definately needs to be.
The Weapons Locker buff is a good thing, but it is and should be just for Baird anyway, which would be the idea if there is only one Engineer anyway.
Jack, i have always believed Jack to be a waste of time, and building Horde around Jack, Forge and the Taps was the stupidiest thing The Coalition has done so far, even more so than Escape.
As for the cost increase, i have no idea why this was implemented, in todays Horde it is dumb, because you still have people not dumping Energy, either through forgetfulness or sheer ignorance, and then you have the stupid, stupid personal skills that cost Energy.
There is no reason why there should be only one Engineer, none at all. It really does make that character unique, just like every other character should be, and needs to be.