I doubt the normal tickets are cheaper. Maybe the prices you see, are only for the reservations. Normal tickets have a different price than a reservation.
You can either plan a journey with more regional trains, or skip France if you don’t want to pay for the extra reservations.
Other countries, especially Germany, Austria and Switzerland, Netherlands, Denmark, UK, Ireland have many trains without reservations.
f you want to travel in France and Italy you need to look at the ticket prices for the different trips at the web site for the local railway company, not the Eurail/Interrail Planner or App. The Planner/App will give you the cost for the seat reservation.
WHat many people do (but perhaps not Svenskarna who always have too much kronor?!) is look at normal prices and use a pass ONLY for the days they make long trips, and buy local tickets for short trips. It may be all different if you follow little Gretha and also do the long trips fra Sverige med taget.
F.e. Can->NI: a BUS-along the coast, is 1€ (advance) or 1,50 by driver. Or there is a local day-train pass Isabella, that can also bring you to Monaco and Grasse (perfume!) on local TER trains.
REServ surcharge of 30€ or more are for long INtern. trips like IT-FR or FR-ES. There are in fact not even such trains on your routing.