Love gratuitous changes to long standard toolsets... sigh...
It's not a recent change and is far from gratuitous....
http://lists.debian.org/debian-devel/2009/03/msg00780.html
Features such as traffic shaping, policy routing and multiple IPs on an interface (not virtual interfaces) either are impossible with net-tools or just don't work very well...
Also love quality error messages "-101" is *sooo* informative ;-)
But the last line should be the important one and shows the proper default route in place, though the even more important one is the route to the local net (2607:f678::/64) which also looks right. It's not a routing issue, it's a neighbor discovery issue:
<centos666.peak.org> [55] # ip neigh show 2607:f678::1 dev eth0 FAILED 207.55.16.1 dev eth0 lladdr 00:26:88:f2:9e:80 REACHABLE
Are you allowing ICMPv6? I don't just mean echo and echo-reply (the pings above) but most of the rest of it too?
IPv6 relies on ICMPv6 heavily for path MTU discovery, neighbour discovery and a whole lot more...