A chunk of the Pace service is peak period service, including the low ridership feeders. Take them out, and about 50% of the ridership is majority legacy services (Pulse, 208, 250, 270, 290, 301, 311, 318, 349, 350, 352, 353, 565, 606, etc).
The exurbans aren't as heavy as the aforementioned but provide some essential connections (272, 554) and (after rewriting the title VI plan) can't be evaluated or suspended for the reasons that legacy routes (apples to cantaloupe).
Express routes is something you can take it or leave it (608, 610, 616 needs employer generators to work, whereas 606 is an core route and the rest of I-90 is supported by grants). I-94 and I-294 expresses are cut for the same reason but maybe they'll return as needed (626 is a legacy connector).
Comparing Pace to CTA isn't a fair nor equitable approach. Density and the dynamics of the inner and outer suburbs vary wildly and the services are far different.