It's unfair to assume that there will be fewer amenities at a subway/GO interchange than the biggest rail hub in Canada? It's also unfair to assume that climate control measures will be worse at an above-grade station than a large station with 3 fully enclosed concourses? Things are always in flux, sure, but Verseter himself has said that he wants to ensure there are cross-platform transfers at East Harbor station, implying a station setup similar to Penn Medicine in Philly, where people disembark one train, wait on the platform for their next train, and board that one.I'm not sure how you could come to this conclusion considering that there are simply no designs to make assumptions about.
You're making a lot of assumptions here on things that either won't hold true if the plans continue to unfold, or on things that frankly none of us know about yet.
Also, doesn't Exhibition only serve the Lakeshore lines (No Milton/Barrie/Kitchener line connections) and won't East Harbor not serve the Richmond Hill line given that it's on the other side of the don river?
Metrolinx has also shown us their service plan goals for the future, and most of the cities I mentioned (Hamilton, Kitchener, Barrie) will not see frequent service.