That is quite enough, thank you! Just because I do not agree with you on how the project should be executed does not give you a right to suggest I am somehow not a transit advocate, or question my motives. Everyone here clearly has the city's best interests in mind, we just have different visions on how to get there. Casting aspersions on one's motives derails the discussion and gives the forum a bad name.
Have you been around here? There are still people here who believe that if you don't like Suburban LRTs, then that means you're simply a car advocate who doesn't want to see trains above ground, taking away space from cars.
As for your actual argument, that line of thinking is exactly what we don't need in transit (except for the part about off the shelf designs, but I highly doubt designing a 75 foot subway car that is otherwise standard in the parts it uses is an insurmountable task).
The issue is things like bespoke train designs is ultimately the type of things that pump up subway costs. I'll be frank for a moment, but I absolutely have a thing for having a consistent uniform design across a metro/train network - this is one of the reasons I like the Moscow Metro so much, and why seeing using custom incompatible rolling stock on Lines 5 and 6 pains me so much (Incompatible to the rest of the Streetcar network). That being said, pushing my personal feelings aside and looking at the on the ground facts, unless you have a really, really strong reason to use custom designs (such as your new line is interlining with an existing segment of the Subway network), all they do jack up the cost often for very minimal gain. The OL sorta had that with Obico yard, and the need to upgrade Greenwood yard, but I don't think that's that big of a justification in turn of having a cheaper line with a more more sensible alignment (minus the lack of Cherry Station, please add a Cherry Station).
Transit is not supposed to be cutting edge, it's supposed to be functional. If the design still works (and manifestly it does, otherwise the TTC would have gone back to the drawing board for the proposed T1 replacement rather than building on more of the same), and there is no urgent argument in favour of doing so, such as wheelchair accessibility or energy efficiency, what need is there to change it, exactly? I'm not saying that this is what's going to happen to the Hitachi trains, but progress for progress' sake is what got us white elephants like the SRT.
The SRT was Progress for Progress Sake, meanwhile the Ontario Line is just catching up to what literally everyone else is doing in the 21st century. There is a difference between being futuristic, and being modern.
Ask any rider on the next subway platform you step on and I'm sure they'll agree, provided they are not Gadgetbahn enthusiasts, that having a proven type of vehicle, albeit with the regular comforts passengers have come to expect in the 21st century, would be superior to having something that is cutting edge and doesn't work.
That's exactly what the Ontario Line is.
And I don't see where you are getting the idea that this "technology" is outdated, anyway, considering I haven't actually said anything at all about the type of technology that should be used on the trains, just their length. If the new Hitachi things were the dimensions of a TTC subway car, but kept everything else intact, they'd hardly be out of date.
It's less about technology, and more about using off the shelf design. It is far cheaper to go to the store and pick out an existing teddy bear, than it is to go to the factory, and commission your own bespoke teddy bear design, especially if you're the only one who has a use case for it.
And why stop there? There is nothing about subway trains that is modern to begin with, they have been around for more than 150 years. If pushing technology to its limits is the goal here, why not make the Ontario Line into a maglev or something? Or ask Elon Musk to build his Hyperloop in its place?
Progress for progrsss' sake is bad.
Overall, this whole post is a strawman on a point nobody is actually making, and makes it seem like you don't actually understand what the Ontario Line is doing.