doesn't more address space just give us more routes to handle?
No. It only makes more possible prefixes. Migrating to IPv6 while keeping the current (IPv4) routing and current business relations, there would be somewhat less routes:
bigger address space -> bigger chunks -> less need to incrementally add prefixes to the same place -> less prefixes
You mean "more address space" -> "individual businesses want to multihome and are willing to pay for their own space" -> more prefixes.
These are different business relations. I know for sure that IPv6 allows us to keep the number of prefixes lower, assuming the current business relations. IPv6 may of course modify the business relations as you described, but I'm not smart enough to know for sure in advance whether that will happen or not. Andras