The 407 is in the middle of nowhere, and very wide, so it is not very walkable. Whereas, most of Highway 7 is walkable. The more I hear of this, the more pointless it sounds.
You're not wrong... however what I would ask is how necessary this really is.
I'm a very vocal on the idea that things like TOD, Urban Fabric, and walkability are extremely overrated when it comes to Transit discussions. While they are very important aspects, especially if we want more efficient infrastructure, thus leading to a more efficient economy, too many people these days seem to fall back to this idea that the only way for a transit line to make sense is if you can plop down Canary Wharf on top of it, which isn't true at all.
In General, one can describe 2 ways in which you can make a transit line/station successful:
1) Urban Fabric and Densification, where you create a neighbourhood/center that feeds off the existence of a transit connection, and build a core that makes doing your day to day tasks convenient.
2) You create a high quality service off the back of strong connections that lead you to those major urban neighbourhoods - and this is the important part.
Let's take a look at York Mills Station. If you weren't familiar with Toronto, you'd think that this station is completely pointless. While it does intersect a major street, the land use is horrible. Its in the middle of a flood plain, surrounded by a golf course, a gas station, some distant apartment buildings, and a small commerical complex at the intersection. Beyond it, its just swaths of detached single family housing. Despite that, back in 2019 it had a larger ridership than
ANY STATION ON WASHINGTON DC'S METRO SYSTEM, INCLUDING TRANSFER STATIONS. It even had larger passenger counts than many Subway stations that are in dense urban areas that are fairly walkable and accessible such as Wellesley, and only slightly less riders than the very urban North York Centre. Now why is that? Why is this station in the middle of nowhere this used? Its because it has amazing bus connections that run every 5 minutes, making the station very convenient to access to by bus.
The same principle could easily apply to the 407 Line. Sure, its location means that for the most part its not going to be sitting next to dense walkable areas (although it will definitely serve major destinations such as RHC, Pearson, and MCC), but if it does its job at providing a very fast circumferential throughout the GTHA, then this won't matter. The way it will be used is:
1) You take the transit (either the bus, the subway, or go) to the line.
2) You take the line close to where your final destination is.
3) You then take local services again to reach your final destination.
In fact, we don't even need to theorize, the existing 407 GO Bus services are on their own some of the most used GO bus services on the network, because they do such a great job of providing a circumferential service in the region, especially since it travels on a lightly used highway thus meaning that travel times are
relatively fast.
Now, would the line be better if instead of straddling the 407, it was instead tunneled under major arterials like Highway 7 in order to more directly serve more developments? Yes, it would. However, doing so would mean ballooning the costs of the project to levels that would simply be too expensive to justify - especially with current day construction prices. Remember, the line is meant to serve regional interests, not local. As such the need for people to take a feeder service to reach the line isn't that crucial. I don't see the reason to hike the price up tenfold, just to more directly serve some developments.