GO is extremely unoptimal (regardless of pricing) if you need to take a bus to get to the station, or if you need to transfer to some other form of transit at Union station.
Some stations are working towards better integration, better indoor facilities, etc.
We are going to witness multiple massively improved GO interchanges on the Eglinton Crosstown LRT, as well as on the new Vaughan Subway extension (
Sheppard West GO+TTC Station). It is already under construction. When finished, changing trains will be
much more similar experience to Yonge-Bloor TTC,
with boarding areas directly above-below each other! Underneath is the subway, and above is the GO station.
From the construction photos, some of the designs are rather impressive, bigger indoor waiting areas, shorter walk between modes, etc. Metrolinx is now really focussed on better connecting stations between themselves and other transit.
All of these stations from this
new Metrolinx mindset,
aren't even open yet, so it will take time, but there are at least 4 or 5 similar designs of "above-below-each-other" stations where one boarding area is GO and the other boarding area (TTC) is either directly above or below. Some existing stations are also planned to be relocated for transfer ease (e.g. rebuild & relocate Oriole GO station underneath Eglinton Ave).
These massively improved GO-TTC interchanges are already being worked on by Metrolinx, and by two decades, we should see more than half a dozen of these GO-wide.
Also, RER will run at increased frequencies during peak, it's not necessarily 15-minutes everywhere. Some of the proposals shows 5 to 8 minute peak service in some core sections, and 15 minute in more outer sections, etc.
Within a decade, at some stations, GO (RERified, minced, diced, SmartTrackized and then shockingly electrified) will be much more frequent and short-wait than catching a Sunday bus. And with much bigger indoor waiting areas at some of these nice interchange stations -- much more comfortable than catching a bus at an outdoor stop.
When this happens, it becomes worthy of superimposing the 416 part of the GO network onto all TTC subway maps, in the
post-fare-intgration-era [MetrolinxEngage.com].